Electromagnetic Waves — Physics STD 12 Science — Question

Photons of energies 1eV and 2eV are successively incident on a metallic surface of work function 0.5eV. The ratio of kinetic energy of most energetic photoelectrons in the two cases will be:

A galvanometer of 10 ohm resistance gives full scale deflection with 0.01 ampere of current. It is to be converted into an ammeter for measuring 10 ampere current. The value of shunt resistance required will be

(a)  ohm

(b) 0.1 ohm

(c) 0.5 ohm

(d) 1.0 ohm

The work-function of a metal is:

In potentiometer a balance point is obtained, when:

A steady current is passing through a linear conductor of non uniform cross-section. The net quantity of charge crossing any cross section per second is:

Consider a wire carrying a steady current, I placed in a uniform magnetic field B perpendicular to its length. Consider the charges inside the wire. It is known that magnetic forces do no work. This implies that:

Zener-diode is used in:

The power of convex lens of focal length 20 cm in dioptre is :

An object is placed 12 cm to the left of a converging lens of focal length 8 cm. Another converging lens of 6 cm focal length is placed at a distance of 30 cm to the right of the first lens.  The second lens will produce

(a) No image	(b) A virtual enlarged image
(c) A real enlarged image	(d) A real smaller image

Wavefront means

(a) All particles in it have same phase

(b) All particles have opposite phase of vibrations(c) Few particles are in same phase, rest are in opposite phase

(c) Few particles are in same phase, rest are in opposite phase

(d) None of these