Physics Past Questions and Answers

In a discharge tube, most of the gas is pumped out so that electricity is conducted at

A Low voltage
B Steady voltage
C High pressure
D Low pressure

Question 67:

The ground stated energy for the hydrogen atom is 5.44 x 10^-19J . If an electron drops from zero energy to ground state, calculate the frequency of the emitted radiation.
[h = 6.6 x 10^-34 Js]

A 5.0 x 10¹⁶ Hz
B 2.0 x 10¹⁶ Hz
C 5.0 x 10¹⁵ Hz
D 2.0 x 10¹⁵ Hz
E No correct option

Question 68:

Transistors are used for the

A Rectification of signals
B Conversion of a.c to d.c
C Amplification of signals
D Conversion of d.c to a.c

Question 69:

Which of the following is a pure semiconductor?

A Carbon
B Silicon
C Transistor
D Phosphorus

Question 70:

The diagram above shows a velocity - time graph. The statement that is true about this motion is that the car

A Has no acceleration between point F and G
B Decelerates between F and H
C Has a constant soeed between points E and F
D Accelerates between points F and G