testing

SI unit of permittivity of free space is-

A charge Q is placed at the centre of the line joining two point charges +q and +q as shown in the figure. If the system of these three charges is in equilibrium then the ratio of charges Q and q is

The force per unit charge is known as

Electric field lines provide information about

Which of the following figures represent the electric field lines due to a single negative charge?

The SI unit of electric flux is

The unit of electric dipole moment is

Consider a region inside which, there are various types of charges but the total charge is zero. At points outside the region

The surface considered for Gauss’s law is called

The total flux through the faces of the cube with side of length a if a charge q is placed at corner A of the cube is

Which of the following statement is true?

Five balls named A to E are suspended using separate threads. Pairs (A, B), (B, D) and (D, A) show electrostatic attraction, while pairs (B, C) and (D, E) show repulsion. Therefore, ball A must be

Two charges +Q and +2Q are situated at the ends of a straight line. Another charge +q is placed at the mid-point of the line, then choose the correct statement regarding the charge +q.

An arrangement of three fixed electric charges is as shown below. In each arrangement, at point P, a test charge +q have been placed. The charges and point P all lie on a straight line. The distances between adjacent items, either between two charges or
between a charge and point P, all are the same.

Correct order of magnitude of force on P in a decreasing order is

A positron and an electron are located in a uniform electric field, they will experience

Electric force at a point is given by \( \displaystyle F=\frac{1}{{4\pi {{\varepsilon }_{0}}}}{{q}_{0}}\int{{\frac{{\sigma ds}}{{{{r}_{0}}^{2}}}\widehat{{{{r}_{0}}}}}}\)

The nature of charges are

A uniformly charged solid cube has its dimensions (a × a × a)cm3. The variation of electric field at r >> a can be represented by

For a uniformly charged cylinder, which of the following figure represents the top view sketch of electric field lines?

The electric field acting at a certain region is given by the expression  E = Ar². A charge
contained in a sphere of radius a centred at the origin of the field will be given by

An electric dipole has a pair of equal and opposite point charges q and − q are
separated by a distance 2x. The axis of the dipole is defined as

An electric dipole of dipole length 2 cm is placed in a uniform electric field intensity 2 × 10⁵ N/C, making an angle 30° with the field. If it experiences a torque equal to 4 N-m, the charge on the dipole is

Which of the following I-V graph represents ohmic conductors?

The resistivity of alloy manganin is

An electric heater is connected to the voltag supply. After few seconds, current gets its steady value then its initial current will be

In the series combination of two or more than  two resistances

Combine three resistors \( \displaystyle 5\Omega ,\,\,4.5\Omega \,\,\And \,3\Omega \) in such a way that the total resistance of this combination is maximum

A cell having an emf ε and internal resistance r is connected across a variable external resistance R. As the resistance R is increased, the plot of potential difference V across R is given by

If n cells each of emf ε and internal resistance r are connected in parallel, then the total emf and internal resistance will be

In a wheatstone bridge if the battery and galvanometer are interchanged then the
deflection in galvanometer will

DIRECTION: Read the two statements Assertion (A) and Reason (R) carefully to mark the correct option out of the options given below:

Assertion: Chemical reactions involved in primary cells are irreversible and in secondary cells are reversible.
Reason: Primary cells can be recharged, but secondary cells cannot be recharged.

DIRECTION: Read the two statements Assertion (A) and Reason (R) carefully to mark the correct option out of the options given below:

Assertion: It the length of the conductor is doubled, the drift velocity will become half of
the original value (keeping potential) difference unchanged).
Reason: At constant potential difference, drift velocity is inversely proportional to the length of the conductor.

DIRECTION: Read the two statements Assertion (A) and Reason (R) carefully to mark the correct option out of the options given below:

Assertion: The 200 W bulbs glows with more brightness than 100 W bulbs.
Reason: A 100 watt bulb has more resistance than a 200 W bulb.

DIRECTION: Read the two statements Assertion (A) and Reason (R) carefully to mark the correct option out of the options given below:

Assertion: Two electric bulbs of 50 Watt and 100 watt are given. When connected in series 50 watt bulb glows more but when connected in parallel 100 watt bulb glows more.
Reason: In series combination, power is directly proportional to the resistance of circuit. But in parallel combination, power is inversely proportional to the resistance of the circuit.

As the temperature increases, the resistance of the metallic conductors increases because

A wire of length l is stretched by 10%, the percentage increase in resistance will be

Two wires are joined together in series. The temperature coefficient of resistance wires are R₁ and R₂ is α₁ and α₂, respectively. The effective temperature coefficient of resistance is

For two incandescent bulbs of rated power P₁ and P₂, if P₁ > P₂. Then, choose the correct statement.

A bulb of rating 60W, 220V is being used as a light source daily. Its circuit is as shown
in the figure below

I. Resistance of the bulb must be lower than 1 kΩ.
II. Current through the bulb is less than 1 A.
III. Energy consumed by the bulb is 60 J/h.

Choose the correct statement(s).

In a household connection, four electrical appliances are used from a single socket. If geyser, refrigerator, bulb and fan uses 4A, 2A, 1A and 1A current respectively, then current received from the main supply by the socket will be

In the given circuit, currents in different branches and value of one resistor are shown in figure. Then, potential at point B with respect to the point A via C and D is

Which of the following statement(s) is/are incorrect?

DIRECTION: Read the two statements Assertion (A) and Reason (R) carefully to mark the correct option out of the options given below:

Assertion: The electron drift velocity is small and the charge on the electron is also small but still, we obtain large current in a conductor.
Reason: This is due to the conducting property of the conductor.

DIRECTION: Read the two statements Assertion (A) and Reason (R) carefully to mark the correct option out of the options given below:

Assertion: During charging, the current flows in opposite directions in a cell.
Reason: Terminal voltage of the cell is higher than the emf of the cell.

The figure (1) shows the experimental set up for verification of Ohm’s law. Graph obtained for this set up is shown in figure (2).

If the resistance R is changed with a new resistance of value 2R and the experiment is repeated again then which of the following will be the correct V-I graph?

When no electric field is present.
I. The electrons will be moving due to thermal motion during which they collide with the fixed ions.

II. An electron colliding with an ion emerges with the same speed as before the collision. However the direction of its velocity after the collision is completely random.

III. At a given time, there is no preferential direction for the velocities of the electrons. Thus, on an average, the number of electrons travelling in any direction will be equal to the number of electrons travelling in the opposite direction. So, there will be no net electric current.

Which of the above statements are correct?

The figure shows three conductors I, II and III of same material, different lengths l, 2l and 3l and of different areas of cross-section 3A, A and 2A respectively.

Arrange them in the increasing order of current drawn from battery.

Which of the following I-V graph represents ohmic conductors ?

The I-V characteristics shown in figure represents

The voltage V and current I graphs for a conductor at two different temperatures T₁ and T₂ are shown in the figure. The relation between T₁ and T₂ is

The graph shows the variation of resistivity with temperature T. The graph can be of

Choose the correct circuit diagram which is equivalent to the circuit diagram given in the figure.

Four resistors R₁, R₂, R₃ and R₄ are connected in different ways. Which of the following combinations will draw the maximum current when connected to a battery ?

A wire of length l is connected to a battery between point A and B as shown in fig (1). The same wire is bent in the form of a circle and then connected to the battery between the points A and B as shown in fig. (2).

The current drawn from the battery

Figure shows a cell in which electrodes P and N are dipped in electrolyte. Points A and B are just adjacent to the electrodes. P is positive electrode and N is negative electrode.

Which of the following is true?

The figure shows the circuit diagram of five resistors, a battery and a switch.If the switch S is closed then current drawn from the battery

A cell having an emf H and internal resistance r is connected across a variable external resistance R. As the resistance R is increased, the plot of potential difference V across R is given by

Which of the following is the correct equation when kirchhoff’s loop rule is applied to the loop BCDEB in clockwise direction?

For the circuit diagram shown in the figure the value of I₁ comes out to be negative. It implies that

The figure shows a circuit diagram of a Wheatstone Bridge’ to measure the resistance G of the galvanometer. The relation \( \displaystyle \frac{P}{Q}=\frac{R}{G}\)

The bridge is at balanced condition in figure. Now the battery and galvanometer are interchanged.

Which of the following  figures show the correct direction of flow of current?

In the figure in balanced condition of wheatstone bridge

Which of the following statement(s) is/are correct for the magnetic field strength at a point due to a long straight conductor?

In a long straight wire placed along Z-axis , a current i flows in the negative z-direction. At a point (x, y) in a plane z = 0, the magnetic field B is

Two particles A and B of masses m_A and m_B, respectively having same charge are moving in a plane. Both particles enter in a uniform magnetic field perpendicular to the plane. If speed of the particles are v_A and v_B respectively, then

An electron is moving in a circular path under the influence of a transverse magnetic field 3.57 × 10⁻² T. If the value of \( \displaystyle \frac{e}{m}\) is  1.76×10¹¹ C/kg, then the frequency of revolution of the electron is

A circle is segmented into 8 equal parts. If current I flows through the circle, then magnetic moment due to given figure is

A constant current I is flowing through a circular coil placed in a uniform magnetic field B as shown in figure, then the

The full scale deflection current of a galvanometer of resistance 1Ω is 5 mA. The value of shunt to be added in series to convert it into a voltmeter of range 5 V is

DIRECTION: Read the two statements Assertion (A) and Reason (R) carefully to mark the correct option out of the options given below:

Assertion: The net force on a closed current loop placed in a uniform magnetic field is zero.
Reason: The torque produced in a conducting loop is zero, when it is placed in a uniform magnetic field such that magnetic field is perpendicular to the plane of the loop.

A strong magnetic field is applied on a stationary electron. Then the electron

In an inertial frame of reference, the magnetic force on a moving charged particle is \(\displaystyle \overrightarrow{F}\)  . Its value in another inertial frame of reference will be

A charged particle is moving on circular path with velocity v in a uniform magnetic field B, if the velocity of the charged particle is doubled and strength of magnetic field is halved, then radius becomes

Two α-particles have the ratio of their velocities as 3 : 2 on entering the field. If they move in different circular paths, then the ratio of the radii of their paths is

If an electron is moving with velocity \( \displaystyle \overrightarrow{v}\) produces a magnetic field \( \displaystyle \overrightarrow{B}\) , then

Current flows through uniform, square frames as shown in the figure. In which case is the magnetic field at the centre of the frame not zero?

Ampere’s circuital law is given by

The correct plot of the magnitude of magnetic field \( \displaystyle {\overrightarrow{B}}\) vs distance r from centre of the wire is, if the radius of wire is R

DIRECTION: Read the two statements Assertion (A) and Reason (R) carefully to mark the correct option out of the options given below:

Assertion: When force is zero, the charged particle follows linear path.
Reason: A charged particle enters in a uniform magnetic field, whose velocity makes an angle θ with magnetic field will cover a linear path.

DIRECTION: Read the two statements Assertion (A) and Reason (R) carefully to mark the correct option out of the options given below:

Assertion: An electron and proton enters a magnetic field with equal velocities, then the
force experienced by proton will be more than electron.
Reason: The mass of proton is 1837 times more than the mass of electron.

DIRECTION: Read the two statements Assertion (A) and Reason (R) carefully to mark the correct option out of the options given below:

Assertion: When a magnetic dipole is placed in a non uniform magnetic field, only a torque acts on the dipole.
Reason: Force would act on dipole if magnetic field is uniform.

DIRECTION: Read the two statements Assertion (A) and Reason (R) carefully to mark the correct option out of the options given below:

Assertion: An ammeter is a connected in series in the circuit.
Reason: An ammeter is a high resistance galvanometer.

DIRECTION: Read the two statements Assertion (A) and Reason (R) carefully to mark the correct option out of the options given below:

Assertion: The magnetic field at the centre of circular coil carrying current changes, if the current through the coil is doubled.
Reason: The magnetic field intensity is dependent on current in conductor.

The conversion of a moving coil galvanometer into a voltmeter is done by

A moving coil galvanometer can be converted into an ammeter by

A current carrying loop is placed in a uniform magnetic field. The torque acting on it does not
depend upon

In a moving coil galvanometer the deflection (Φ) on the scale by a pointer attached to the spring is

The magnetic moment of a current I carrying circular coil of radius r and number of turns N
varies as

Which of the following radiations has the least wavelength?

Which of the following has/have zero average value in a plane electromagnetic wave ?

The ratio of electric field vector E and magnetic field vector H i.e., \(\left( {\frac{E}{H}} \right)\) has the dimensions of

The ozone layer absorbs radiation of wavelengths

The speed of electromagnetic wave in vacuum depends upon the source of radiation. It

In which one of the following regions of the electromagnetic spectrum will the vibrational motion of molecules give rise to absorption?

The oscillating electric and magnetic vectors of an electromagnetic wave are oriented along

Biological importance of ozone layer is

Direction: For given questions two statements are given-one labelled Assertion (A) and the other labelled Reason (R).

Assertion: Displacement current goes through the gap between the plates of a capacitor when the charge of the capacitor does not change.
Reason: The displacement current arises in the region in which the electric field is constant with time.

Direction: For given questions two statements are given-one labelled Assertion (A) and the other labelled Reason (R).

Assertion: Electromagnetic wave are transverse in nature.
Reason: The electric and magnetic fields in electromagnetic waves are perpendicular to each other and the direction of propagation.

Direction: For given questions two statements are given-one labelled Assertion (A) and the other labelled Reason (R).

Assertion: Electromagnetic waves interact with matter and set up oscillations.
Reason: Interaction is independent of the wavelength of the electromagnetic wave.

Direction: For given questions two statements are given-one labelled Assertion (A) and the other labelled Reason (R).

Assertion: Electromagnetic waves carry energy andmomentum.
Reason: Electromagnetic waves can be polarised.

Direction: For given questions two statements are given-one labelled Assertion (A) and the other labelled Reason (R).

Assertion: The velocity of electromagnetic waves depends on electric and magnetic properties of the medium.
Reason: Velocity of electromagnetic waves in free space is constant.

The current in the electric circuit which arises due to flow of electrons in the connecting wires of the circuit in a defined closed path is called

Displacement current goes through the gap between the plates of a capacitor when the charge on the capacitor

Displacement current is

The displacement current is

If \(\overrightarrow E \) and \(\overrightarrow {B\,} \) represent the electric and magnetic field vectors of an electromagnetic wave, then the direction of propagation of the electromagnetic wave, is along

According to Maxwell’s hypothesis, a changing electric field gives rise to

An electromagnetic wave propagating along north has its electric field vector upwards. Its magnetic field vector point towards

The electromagnetic waves

Which of the following type of radiations are radiated by an oscillating electric charge?

If \(\overrightarrow E \) and \(\overrightarrow {B\,} \) are the electric and magnetic field vectors of e.m. waves then the direction of propagation of e m. wave is along the direction of

According to Maxwell’s equation the velocity of light in any medium is expressed as

The electromagnetic waves do not transport

The amplitudes of electric and magnetic fields related to each other are

In an electromagnetic wave, the direction of the magnetic induction \(\overrightarrow {B\,} \) is

The speed of electromagnetic wave is same for

A plane electromagnetic wave is incident on a material surface. If the wave delivers momentum p and energy E, then

We consider the radiation emitted by the human body.
Which one of the following statements is true?

The decreasing order of wavelength of infrared, microwave, ultraviolet and gamma rays is

X-rays, gamma rays and microwaves travelling in vaccum have

Radio waves diffract around building, although light waves do not. The reason is that radio waves

Microwaves are detected by

Which of the following electromagnetic waves has the longest wavelength?

Which of the following is of shortest wavelength?

The range of wavelength of visible light is

Which of the following is not electromagnetic waves?

Which of the following electromagnetic radiations have the smallest wavelength?

Which of the following rays has minimum frequency?

An accelerated electron would produce

Which of the following is the infrared wavelength?

The wavelength of X-ray is of the order of

Radio waves of constant amplitude can be generated with

Radio waves do not penetrate in the band of

What is the cause of “Green house effect”?

If vs, vx and vm are the speed of soft gamma rays, X-rays and microwaves respectively in vacuum, then

The waves which are electromagnetic in nature are

In electromagnetic spectrum, the frequencies \(\gamma – {\rm{Rays}}\), X-rays and ultraviolet rays are denoted by n₁, n₂ and n₃ respectivelythen

Ultraviolet spectrum can be studied by using a

The ozone layer in the atmosphere absorbs

Which one of the following has the maximum energy?

Which one of the following has the shortest wavelength?

When electromagnetic waves enter the ionised layer of ionosphere, then the relative permittivity i.e. dielectric constant of the ionised layer

Ultraviolet rays coming from sun are absorbed by

The EM waves when travel into different media gets

The absorption of radio waves by the atmosphere depends upon

The velocity of all radio waves in free space is 3 × 10⁸ m/s. The frequency of a radio wave of wavelength 150m is

The polarisation of electromagnetic wave is in

If the frequency of EM radiations is halved then the energy of EM radiation will become

For television broadcasting the frequency employed is normally

Electromagnetic waves of frequency …. are reflected from ionosphere.

When an electromagnetic wave enters an ionised layer of earth’s atmosphere present in ionosphere

An electron oscillating with a frequency of 3 × 10⁶ Hz, would generate

The cellular mobile radio frequency band is

Select the wrong statement. EM waves

Ozone layer above earth’s atmosphere will not

Intensity of electromagnetic wave will be

The frequency of electromagnetic wave, which best suited to observe a particle of radii 3 × 10^–4 cm is of the order of

If \(\lambda = 10\mathop {\rm{A}}\limits^{\rm{o}} \) then it corresponds to

10 cm is a wavelength corresponding to the spectrum of

In an electromagnetic wave

The electric and the magnetic field associated with an E.M. wave, propagating along the +z-axis, can be represented by

The condition under which a microwave oven heats up a food item containing water molecules most efficiently is

Which of the following is/are true for electromagnetic waves?

I. They transport energy.
II. They have momentum.
III. They travel at different speeds in air depending on their frequency

Electromagnetic radiation belonging to _________ region of spectrum is called light.

The turning back of light into the same medium after incident on a boundary separating two media is called

A point source of light is placed in front of a plane mirror. Then

The field of view is maximum for

A virtual image larger than the object can be obtained by

An object is placed 40 cm from a concave mirror of focal length 20 cm. The image formed is

All of the following statements are correct except

A person is six feet tall. How tall must a plane mirror be if he is able to see his entire length?

The image formed by a concave mirror is

For reflection through spherical surfaces, the normal at the point of incidence is

Which of the following (referred to a spherical mirror) depends on whether the rays are paraxial or not?

Which of the following is correct for the beam which enters the medium?

When light is refracted, which of the following does not change ?

Total internal reflection can take place only if

The difference between reflection and total internal reflection is that

When the angle of incidence of a light ray is greater than the critical angle it gets

Which of the following phenomena is used in optical fibres ?

Critical angle of light passing from glass to water is minimum for

Which of the following is not due to total internal reflection?

Identify the wrong sign convention

The apparent flattening of the sun at sunset and sunrise is due to

The speed of light in an isotropic medium depends on

A parallel beam of light is incident on a converging lens parallel to its principal axis. As one moves away from thelens on the other side on its principal axis, the intensity of light

The focal length of a converging lens are \({f_V}\,\,and\,\,{f_R}\)for violet and red light respectively. Then