## Class/Course - Class XII

### Subject - Physics

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

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• 1. Electric Charges and Fields - Quiz

1. A charge Q is placed at each of the opposite comers of a square. A charge q is placed at each of the other two corners. If the net electrical force on Q is zero , then Q/q equals
a) - 2√2
b) -1
c) 1
d) -1/√2

2. A spherical portion hs been removed from a solid sphere having a charge distributed uniformly in its volume in the figure.
The electric field inside the empited space is
a) Zero everywhere
b) Non-zero and uniform
c) Non-uniform
d) Zero only at its centre

• 2. Electrostatic Potential and Capacitance - Quiz

1. Let P(r) = (Q/πR4) r be the charge density distribution for a solid sphere of radius R and total charge Q. For a point (P) inside the sphere at distance r1 from the centre of the sphere, the magnitude of electric field is
a) 0
b)
c)
d)

2. A parallel plate capacitor with air between the plates has a capacitance of 9 p F. The separation between its plates is d . The space between the plates is now filied with two dielectrics. One of the dielectrics has dielectric constant k1 = 3 and thickness d/3 while the other one has dielectric constant k2 = 6 and thickness 2d/3. Capacitance of the capacitor is now
a) 1.8 p F
b) 45 p F
c) 40.5 p F
d) 20.25 p F

• 3. Current Electricity - Quiz

1. A cell of emf E volt with no internal resistance is connected to a wire whose cross section changes. The wire has three sections of equal length. The middle section has a radius a, whereas the radius of the outer two sections is 2a. The ratio of the pote
a) 100 ω
b) 200 ω
c) 50 ω
d) 150 ω

2. Which of the following does not obey ohm`s law?
a) Copper
b) Al
c) Diode-valve
d) None

• 4. Moving Charges and Magnetism - Quiz

1. The magnetic field at O due to current in the infinite wire forming a loop as shown in figure is

a) $\frac{\mu _{0}I}{4\pi d}(cos\phi _{1}+cos\phi _{2})$
b) $\frac{\mu _{0}}{4\pi }\frac{2I}{d}(tan\theta _{1}+tan\theta _{2})$
c) $\frac{\mu _{0}}{4\pi }\frac{I}{d}(sin\phi _{1}+sin\phi _{2})$
d) $\frac{\mu _{0}}{4\pi }\frac{I}{d}(cos\theta _{1}+sin\theta _{2})$

2. Two wires AO and OC carry equal currents i as shown in figure. One end of both the wires extends to infinity. Angle AOC is α

The magnitude of magnetic field at a point P on the bisector of these two wires at a distance r from point O is
a) $\frac{\mu _{0}}{2\pi }\frac{i}{r}cot\left ( \frac{\alpha }{2} \right )$
b) $\frac{\mu _{0}}{4\pi }\frac{i}{r}cot\left ( \frac{\alpha }{2} \right )$
c) $\frac{\mu _{0}}{2\pi }\frac{i}{r}\frac{\left ( 1+cos\frac{\alpha }{2} \right )}{sin\left ( \frac{\alpha }{2} \right )}$
d) $\frac{\mu _{0}}{4\pi }\frac{i}{r}\left ( \frac{\alpha }{2} \right )$

• 5. Magnetism and Matter - Quiz

1. The material suitable for making electromagnets should have
a) High retentivity and high coercivity
b) Low retentivity and low coercivity
c) High retentivity and low coercivity
d) Low retentivity and high coercivity

2. A vertical circular coil of radius 0.1 m and having 10 turns carries a steady current. When the plane of the coil is normal to the magnetic meridian, a neutral point is observed at the centre of the coil. If BH = 314 x 10-4 T, the current in the coil is
a) 0.5 A
b) 0.25 A
c) 2A
d) 1A

• 6. Electromagnetic Induction - Quiz

1. A conducting rod PQ of length l = 2 m is moving at a speed of 2 ms-1 making an angle of 300 with its length. A uniform magnetic field B = 2 T exists in a direction perpendicular to the plane of motion. Then

a) VP - VQ = 8V
b) VP - VQ = 4V
c) VQ - VP = 8V
d) VQ -VP = 4V

2. If L and R denote inductance and resistance, then dimensions of L/R is
a) M0L0T0
b) M0L0T
c) M2L0T2
d) MLT2

• 7. Alternating Current - Quiz

1. A resistor and an inductor are connected to an ac supply of 120 V and 50 Hz. The current in the circuit is 3A . If the power consumed in the circuit is 108 W, then the resistance in the circuit is
a) 12 Ω
b) 40 Ω
c) $\sqrt{(52\times 28)}\Omega$
d) 360 Ω

2. A circuit has a resistance of 11Ω, an inductive reactance of 25Ω and a capacitance reactance of 18Ω. It is connected to an a.c. source of 260 V and 50Hz. Current through the circuit (in amperes) is
a) 11
b) 15
c) 18
d) 20

• 8. Electromagnetic Waves - Quiz

1. The electric and magnetic field of an electromagnetic wave are
a) In opposite phase & perpendicular to each other.
b) In opposite phase and parallel to each other.
c) In phase and perpendicular to each other.
d) In phase and parallel to each other.

2. Which of the following statements is true?
a) Velocity of light is constant in all media
b) Velocity of light in vacuum is maximum
c) Velocity of light is same in all reference frames
d) Is same for all of them

• 9. Ray Optics and Optical Instruments - Quiz

1. An equiconvex lens is cut two halves along (i)XOX and (ii) YOY as shown in the figure. Let ƒ , ƒ , ƒ, be the focal lengths of the complete lens, of each half in case (i) and of each half in case (ii), respectively.

Choose the correct statement from the following
a) ƒ = 2ƒ , ƒ = ƒ
b) ƒ = ƒ , ƒ = ƒ
c) ƒ = 2ƒ , ƒ = 2ƒ
d) ƒ = ƒ, ƒ = 2ƒ

2. An object is put at a distance of 5 cm from the first focus of a convex lens of focal length 10 cm. If a real image is formed its distance from the lens will be
a) 15 cm
b) 20 cm
c) 25 cm
d) 30 cm

• 10. Wave Optics - Quiz

1. Two light waves having the same wavelength λ in vaccum are in phase initially . Then , the first ray travels a path of length L 1 through a medium of refractive index μ 1 . The secondary ray travels a path of length L 2 through a medium of recfractive index μ 2 . The two waves are then combined to observe interference effects. The phase difference between the two, when they interfere, is
a) $\frac{2\pi}{\lambda}\left (L_{1} - L_{2} \right )$
b) $\frac{2\pi}{\lambda}\left (\mu_{1}L_{1} - \mu_{2}L_{2}\right )$
c) $\frac{2\pi}{\lambda}\left (\mu_{2}L_{1} - \mu_{1}L_{2}\right )$
d) $\frac{2\pi}{\lambda}\left [\frac{L}{\mu_{1}} - \frac{L_{2}}{\mu_{2}} \right ]$

2. The theory associated with secondary wavelets is
a) Doppler effect
b) Special theory of relativity
c) Huygens wave theory
d) None of these

• 11. Dual Nature of Radiation and Matter - Quiz

1. Out of a photon and an electrons, the equation E=pc is valid for
a) both
b) neither
c) photon only
d) electron only

2. Electrons traveling at a velocity of 2.4×106ms-1 enter a region of crossed electric and magnetic fields shown in Figure. If the electric field is 3.0×106 Vm and the flux density of the magnetic field is 1.5 T, electrons upon entering the region of the crossed fields will

a) continue to travel underdeflected in their original direction
b) be deflected upward in the plane of the disgram
c) be deflected downward on the plane of the diagram
d) none of the above

• 12. Nuclei - Quiz

1. Half life of a radioactive substance is 20 minutes. The time between 20% and 80% decay will be
a) 25 minutes
b) 20 minutes
c) 40 minutes
d) 20 minutes

2. When 3Li7 nuclei are bombarded by protons, and the resultant nuclei are 4Be8, the emitted particles will be
a) Neutrons
b) Alpha particles
c) Beta particles
d) Gamma photons

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

1. The symbolic representataio of four logic gates are given below:

The logic symbols for OR, NOT and NAND gates are respectively:
a) (iii), (iv) , (ii)
b) (iv), (i), (iii)
c) (iv), (ii), (i)
d) (i), (iii), (iv)

2. Which logic gate is represented by the following combination of logic gates?

a) OR
b) NAND
c) AND
d) NOR

• 14. Communication Systems - Quiz

1. An antenna is of height 500 m. What will be its range (Radius of the earth is 6400 km)?
a) 800 km
b) 100 km
c) 50 km
d) 80 km

2. The wavelength of electromagnetic waves employed for space communication lie in the range of
a) 1 mm to 30 m
b) 1 mm to 300 m
c) 1 mm to 3 km
d) 1 mm to 30 km

• 15. Atoms - Quiz

1. The circumference of the second Bohr orbit of electron in hydrogen atom is 600 nm. The potential difference that must be applied between the plates so that the electrons have the de Broglie wavelength corresponding in this circum ference is
a) $10^{-5} V$
b) $\frac{5}{3} \times 10^{-5}V$
c) $5 \times 10^{-5}V$
d) $3\times 10^{-5}V$

2. If elements with principle quantum number n > 4 were not allowed in nature, the number of possible elements would be
a) 60
b) 32
c) 4
d) 64

• 16. Electric flux and Gauss Law - Quiz

1. A cylinder of length L and radius b has its axis coincident with the x-axis. The electric field in this region is $\vec{E}$ = $200\hat{i}$. Find the flux through the left end of the cylinder.
a) 0
b) 200 πb2
c) 100 πb2
d) -200 πb2

2. The electric flux from a cube of edge l is φ. If an edge of the cube is made 2l and the charge enclosed is halved, its value will be
a) 4φ
b) 2φ
c) φ/2
d) φ

• 17. Electrical Measuring Instrument - Quiz

1. An 80Ωgalvanometer deflects full-scale for a potential of 20mV. A voltmeter deflecting full-scale of 5V is to be made using this galvanometer. We must connect
a) a resistance of 19.92 kΩ parallel to the galvanometer
b) a resistance of 19.92kΩ in series with the galvanometer
c) a resistance of 20kΩ parallel to the galvanometer
d) a resistance of 20kΩ in series with the galvanometer

2. A milliammeter of range 10mA has coil of resistance 1Ω. To use it as an ammeter of range 1A, the required shunt have a resistance of
a) $\frac{1}{101}\Omega$
b) $\frac{1}{100}\Omega$
c) $\frac{1}{99}\Omega$
d) $\frac{1}{9}\Omega$

• 18. Heating Effect of Current - Quiz

1. An electric kettle (rated accurately at 2.5 kW) is used to heat 3kg of water from 150C to boiling point . It takes 9.5 min. Then the amount of heat that has been lost is
a) 3.5 x 105 J
b) 7 x 108J
c) 3.5 x 104 J
d) 7 x 108 J

2. Two similar headlight lamps are connected in parallel to each other. Together, they consume 48 W from a 6 V battery. What is the resistance of each filament?
a) 6Ω
b) 4Ω
c) 3.0Ω
d) 1.5Ω