## Class/Course - Class XII

### Subject - Physics

#### Total Number of Question/s - 5154

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• 1. Electric Charges and Fields - Quiz

1. It is required to hold equal charges q in equilibrium at the corners of a square. What charge when placed at the center of the square will do this?
a) $-\frac{q}{2}\left (1 + 2\sqrt{2} \right )$
b) $\frac{q}{2}\left (1 + 2\sqrt{2} \right )$
c) $\frac{q}{4}\left (1 + 2\sqrt{2} \right )$
d) $-\frac{q}{4}\left (1 + 2\sqrt{2} \right )$

2. At a distance r from a point located at origin in space, the electric potential varies as V = 10r. Find the electric field at$\vec{r}$ = $3\hat{i} + 4\hat{j} - 5\hat{k}$
a) $\sqrt{2}\left (3\hat{i} + 4\hat{j} - 5\hat{k} \right )$
b) $-\sqrt{2}\left (3\hat{i} + 4\hat{j} - 5\hat{k} \right )$
c) $-\sqrt{3}\left (3\hat{i} + 4\hat{j} - 5\hat{k} \right )$
d) None of these

• 2. Electrostatic Potential and Capacitance - Quiz

1. A thin spherical conducting shell of radius R has a charge q. Another charges Q is placed at the centre of the shell. The electrostatic potential at a point P a distance R/2 from the centre of the shell is
a) (q + Q)/ 4πε0 2/R
b) 2Q/4πε0R
c) 2Q/ 4πε0 R - 2q/ 4πε0R
d) 2Q / 4πε0R + q/4πε0R

2. Consider a neutral conducting sphere . A positive point charge is placed outside the sphere. The net charge on the sphere is then,
a) Negative and distributed uniformly over the surface of the sphere.
b) Negative and appears only at the point on the sphere closest to the point charge.
c) Negative and distributed non-uniformly over the entire surface of the sphere.
d) Zero

• 3. Current Electricity - Quiz

1. A wire of length L and three identical cells of negligible internal resistances are connected in series. Due to the current, the temperature of the wire is raised by ΔT in a time t. A number N of similar cells is now connected in series with a wire of the same material and cross section but of length 2L. The temperature of the wire is raised by the same amount ΔT in the same time t. The value of N is
a) 4
b) 6
c) 8
d) 9

2. In the circuit shown fig., calculate the current through 6V battery.

a) (1/4)A
b) (1/8)A
c) (1/2)A
d) none of these

• 4. Moving Charges and Magnetism - Quiz

1. Two concentric coils, each of radius equal to 2π cm, are placed at right angles to each other. Currents of 3A and 4A, respectively, are flowing through the two coils. The magnetic induction, in Wb m-2, at the centre of the coils will be
0 = 4π × 10-7 Wb(Am)-1]
a) 5 × 10-5
b) 7 × 10-5
c) 12 × 10-5
d) 10-5

2. If an electron and a proton having same momenta enter perpendicular to a magnetic field, then
a) Curved path of electron and proton will be same (ignoring the sense of revolution)
b) They will move undeflected
c) Curved path of electron is more curved than that of the proton
d) Path of proton is more curved

• 5. Magnetism and Matter - Quiz

1. The magnetic susceptibility of a material of a rod is 499. Permeability of vacuum is 4π x 10-7 H/m. Absolute permeability of the material of the rod in henry/ meter is
a) π x 10-4
b) 2π x 10-4
c) 3π x 10-4
d) 4π x 10-4

2. Two wires of same length are shaped into a square and a circle. If they carry same current, then ratio of the magnetic moments is
a) 2 : π
b) π : 2
c) π : 4
d) 4 : π

• 6. Electromagnetic Induction - Quiz

1. As a result of change in the magnetic flux linked to the closed loop shown in the figure, an emf V volt is induced in the loop. The work done (joule) in taking a charge Q coulomb once along the loop is

a) QV
b) Zero
c) 2QV
d) QV/2

2. The capacitor of an oscillatory circuit of frequency 10,000 Hz is enclosed in a container. When the container is evacuated, the frequency changes by 50 Hz, the dielectric constant of the gas is
a) 1.1
b) 1.01
c) 1.001
d) 1.0001

• 7. Alternating Current - Quiz

1. The resistance and inductance of series circuit are 5 Ω and 20 H respectively. At the instant of closing the switch, the current is increasing at the rate 4 A-s. The supply voltage is
a) 20 V
b) 80 V
c) 12 V
d) 100 V

2. In a series resonant LCR circuit, the voltage across R is 100 volts and R - 1kΩ with C = 2μF. The resonant frequency ω is 200 rad/s. At resonance, the voltage across L is
a) 4 x 10-3 V
b) 2.5 x 10-2 V
c) 40 V
d) 250 V

• 8. Electromagnetic Waves - Quiz

1. The structure of solids is investigated by using
a) cosmic rays
b) X-rays
c) γ-rays

2. If ε0 and μ0 are respectively the electric permittivity and magnetic permeability of free space, ε and μ are the corresponding quantities in a medium, the index of refraction of the medium is
a) $\sqrt{\frac{\varepsilon _{0} \mu_{0}}{\varepsilon \mu_{0}}}$
b) $\sqrt{\frac{\varepsilon \mu}{\varepsilon _{0}\mu_{0}}}$
c) $\sqrt{\frac{\varepsilon_{0} \mu_{0}}{\varepsilon \mu_{0}}}$
d) $\sqrt{\frac{\varepsilon }{\varepsilon _{0}}}$

• 9. Ray Optics and Optical Instruments - Quiz

1. A plane glass mirror of thickness 3 cm of material of μ = 3/2 is silvered on the back surface . When a point object is placed 9 cm from the front surface of the mirror, then the position of the brightest image from the front surface is
a) 9 cm
b) 11 cm
c) 12 cm
d) 13 cm

2. Concave and convex lenses are placed touching each other. The ratio of magnitudes of their power is 2: 3. The focal of the system is 30 cm. Then the focal lengths of individual lenses are
a) -75 , 50
b) -15, 10
c) 75, 50
d) 75, -50

• 10. Wave Optics - Quiz

1. In young double slit experiment with monochromatic light, the central fringe will be
a) Coloured
b) White
c) Bright
d) Black.

2. The size of an obstacle in order to observe diffraction of light must be
a) Of any order
b) Of the order of wavelength
c) Much larger than wavelength
d) Much smaller than wavelength

• 11. Dual Nature of Radiation and Matter - Quiz

1. Formation of covalent bonds in compounds exhibits
a) Wave nature of electron
b) Particle nature of electron
c) Both wave and particle nature of electron
d) None of these

2. A particle with rest mass m0 is moving with speed c. The de Brogile wavelength associated with it is
a) Zero
b) Infinity
c) hv/m0c
d) m0c/hv

• 12. Nuclei - Quiz

1. Which one of the following is a possible nuclear reaction?
a)
b)
c)
d)

2. The mass of proton is 1.0073 u and that of neutron is 1.00087 u (u = atomic mass unir). The binding energy of 24He is
a) 0.0305 erg
b) 28.4 MeV
c) 0.061 u
d) 0.0305 J

• 13. Semiconductor Electronics: Materials, Devices and Simple Circuit - Quiz

1. When a p-n diode is reversed biased, then
a) No current flows
b) The depletion region is increased
c) The depletion region is reduced
d) The height of the potential barrier is reduced.

2. A solid which is transparent to visible light and whose conductivity increase with temperature is formed by
a) Metallic bonding
b) Ionic bonding
c) Covalent bonding
d) Van der Waals interactions

• 14. Communication Systems - Quiz

1. Radio waves of constant amplitude can be generated with
a) Filter
b) Rectifier
c) FET
d) Oscillator

2. The space waves which are affected seriously by atmospheric conditions are
a) MF
b) HUF
c) VHF
d) UHF

• 15. Atoms - Quiz

1. If a hydrogen atom amits a photon of energy 12.1 eV, its orbital angular momentum changes by ΔL . Then, ΔL equals
a) $1.05 \times 10^{-34}Js$
b) $2.11 \times 10^{-34}Js$
c) $3.16 \times 10^{-34}Js$
d) $4.22 \times 10^{-34}Js$

2. If 13.6 e V energy is required to ionize the hydrogen atom, then the energy required to remove an electron from n = 2 is
a) 10.2 e V
b) 0 e V
c) 3.4 e V
d) 6.8 e V

• 16. Electric flux and Gauss Law - Quiz

1. A hollow metallic sphere of radius 10cm is given a charge of 3.2 × 10-9C. The electric intensity at a point 4cm from the center is
a) 9 × 10-9 NC-1
b) 299 NC-1
c) 2.88 NC-1
d) zero

2. A sphere of radius R carries charge such that its volume charge density is proportional to the square of the distance from the center. What is the ration of the magnitude of the electric field at a distance 2R from the center to the magnitude of the electric field at a distance of R/2 from the center?
a) 1
b) 2
c) 4
d) 8

• 17. Electrical Measuring Instrument - Quiz

1. The resistance of a galvanometer is 10Ω. It gives full-scale deflection when 1 mA current is passed. The resistance connected in series for converging it into a voltmeter of 2.5V will be
a) 24.9 Ω
b) 249 Ω
c) 2490 Ω
d) 24900 Ω

2. The emf of the driver cell of a potentiometer is 2V, and its internal resistance is negligible. The length of the potentiometer wire is 100cm, and resistance is 5Ω. How musch resistance is to be connected in series with the potentiometer wire to have a potential gradient of 0.05m V cm-1?
a) 1990Ω
b) 2000Ω
c) 1995Ω
d) none of these

• 18. Heating Effect of Current - Quiz

1. Two identical heaters rates 220V, 100 W are plces in series with each other across 220V line; then the combined power is
a) 1000 W
b) 2000 W
c) 500 W
d) 4000 W

2. Two electric bulbs A and B are rated 60 and 100W, respectively . If thwy are connected in parallel to the same source, then
a) both the bulbs sraw the same current
b) bulb A draws more current than bulb B
c) bulb B draws more current than bulb A
d) currents drawn in the bulbs are in the ratio of their resistances