Physics Past Questions and Answers

The energy associated with the emitted photon when a mercury atom changes from one state to another is 3.3 ev. calculate the frequency of the photon.
[e = 1.6 x 10^-19c; h = 6.6 x 10^-13js]

A 1.3 x 10^-15 Hz
B 3.1 x 10⁵² Hz
C 3.2 x 10^-53 Hz
D 8.0 x 10¹⁴ Hz

Question 27:

The process through which free electrons leave the surface of hot metal is known as?

A Photon emission
B Photo emission
C Thermionic emission
D Electron emission

Question 28:

The battery connection that permits current to flow across a p-n junction is called?

A Reverse baised
B Forward baised
C Amplification.
D Rectification

Question 29:

One of the properties of gamma rays is that they are?

A Neutral
B Massive
C Positively charged
D Negatively charged

Question 30:

A radioactive element has a half life of 4 days. The fraction that has decayed in 16 days is?

A (15)/16
B (1)/16
C (3)/4
D (1)/4