Electrostatic Potential and Capacitance — Physics STD 12 Science — Question

Thermal neutrons are those which

(a) Are at very high temperature

(b) Move with high velocities

(c) Have kinetic energies similar to those of surrounding molecules

(d) Are at rest

If the light moving in a straight line bends by a small but fixed angle, it may be a case of:

1. Reflection.
2. Refraction.
3. Diffraction.
4. Dispersion.

The refractive indices of violet and red light are 1.54 and 1.52 respectively. If the angle of prism is 10°, then the angular dispersion is

(a) 0.02

(b) 0.2

(c) 3.06

(d) 30.6

Of the following properties, the photon does not possess:

A prism (μ = 1.5) has the refracting angle of 30°. The deviation of a monochromatic ray incident normally on its one surface will be (sin 48° 36’ = 0.75)

(a) 18° 36’

(b) 20° 30’

(c) 18°

(d) 22°1’

The charge of an electron is 1.6 × 10^–19 C.  How many electrons strike the screen of a cathode ray tube each second when the beam current is 16 mA

(a) 1017

(b) 1019

(c) 10–19

(d) 10–17

An electric dipole is placed at an angle of 30° to a non-uniform electric field. The dipole will experience:

A coil of N turns and mean cross-sectional area A is rotating with uniform angular velocity w about an axis at right angle to uniform magnetic field B. The induced e.m.f. E in the coil will be

(a) NBA sinwt

(b) NB w sinwt

(c) NB/A sinwt

(d) NBA w sinwt

When light propagates in vaccum there is an electric field and a magnetic field. Which of the following is not true about these field?

A convex lens is used to form real image of an object on a screen. It is observed that even when the positions of the object and that screen are fixed there are two positions of the lens to form real images.  If the heights of the images are 4 cm and 9 cm respectively, the height of the object is

(a) 2.25 cm

(b) 6.00 cm

(c) 6.50 cm

(d) 36.00 cm