Electrostatic Potential and Capacitance — Physics STD 12 Science — Question

The critical angle between an equilateral prism and air is 45°. If the incident ray is perpendicular to the refracting surface, then

(a) After deviation it will emerge from the second refracting surface

(b) It is totally reflected on the second surface and emerges out perpendicularly from third surface in air

(c) It is totally reflected from the second and third refracting surfaces and finally emerges out from the first surface

(d) It is totally reflected from all the three sides of prism and never emerges out

What is the order of magnitude of the resistance of a dry human body?

The absorption of radio waves by the atmosphere depends upon:

Water molecule is the example of:

An electric dipole is placed in a uniform electric field. The net electric force on the dipole.

1. Is always zero.
2. Depends on the orientation of the dipole.
3. Can never be zero.
4. Depends on the strength of the dipole.

If λ =10Å, then it corresponds to

(a) Infra-red

(b) Microwave

(c) Ultra-violet

(d) X-rays

The combination of the gates shown in the figure below produces

(a) NOR gate

(b) OR gate

(c) AND gate

(d) XOR gate

A biconvex lens forms a real image of an object placed perpendicular to its principal axis. Suppose the radii of curvature of the lens tend to infinity. Then the image would

(a) Disappear

(b) Remain as real image still

(c) Be virtual and of the same size as the object

(d) Suffer from aberrations

A single slit of width 0.20 mm is illuminated with light of wavelength 500 nm. The observing screen is placed 80 cm from the slit. The width of the central bright fringe will be

(a) 1 mm

(b) 2 mm

(c) 4 mm

(d) 5 mm