Electric Charges and Fields — Physics STD 12 Science — Question

The threshold wavelength for photoelectric effect of a metal is 6500 Å. The work function of the metal is approximately

(a) 2 eV

(b) 1 eV

(c) 0.1 eV

(d) 3 eV

A radioactive substance has an average life of 5 hours. In a time of 5 hours          

(a) Half of the active nuclei decay	(b) Less than half of the active nuclei decay
(c) More than half of the active nuclei decay	(d) All active nuclei decay

If light is passed through a double-slit opening and falls onto a screen, Identify the pattern produced on the screen.

Maxwell’s equations describe the fundamental laws of

(a) Electricity only

(b) Magnetism only

(c) Mechanics only

(d) Both (a) and (b)

Wave nature of light is verified by

(a) Interference

(b) Photoelectric effect

(c) Reflection

(d) Refraction

Two photons having:

Five resistors of given values are connected together as shown in the figure. The current in the arm BD will be

(a) Half the current in the arm ABC	(b) Zero
(c) Twice the current in the arm ABC	(d) Four times the current in the arm ABC

A wavefront is an imaginary surface where:

A radio receiver antenna that is 2 m long is oriented along the direction of the electromagnetic wave and receives a signal of intensity 5 . The maximum instantaneous potential difference across the two ends of the antenna is

(a) 1.23 mV

(b) 1.23 mV

(c) 1.23 V

(d) 12.3 mV

In the experiment of potentiometer, at balance point, there is no current in the: