Physics Questions and Answers
If you want to learn more about the nature and properties of matter and energy or you're simply preparing for a Physics exam, these Physics past questions and answers are ideal for you.
If you want to learn more about the nature and properties of matter and energy or you're simply preparing for a Physics exam, these Physics past questions and answers are ideal for you.
When electrical power is transmitted over long distances, the voltage is stepped up so that
the resistance of the wire may be increased proportionately to the potential difference
the time of transmissions between the generating and the receiving stations may be reduced
there is increased current to produce brighter lights.
the rate of electrical consumption is increased.
the energy waste may be minimised as the current is lowered.
Correct answer is E
No explanation has been provided for this answer.
Which of the following is used in a nuclear reactor to slow down fast moving neutrons?
graphite rods
carbon dioxide gas
liquid sodium metal
concrete shield
boron rods
Correct answer is A
No explanation has been provided for this answer.
The half-life of a radioactive substance is 2 seconds. Calculate the decay constant.
2.890 s-1
1.445 s-1
0.576 s-1
0.347s-1
0.152 s-1
Correct answer is D
\(T_{\frac{1}{2}} = \frac{\ln 2}{\lambda}\)
where \(T_{\frac{1}{2}}\) = half-life of element; \(\lambda\) = decay constant.
= \(\frac{0.693}{\lambda}\)
\(\therefore 2 = \frac{0.693}{\lambda}\)
\(\lambda = \frac{0.693}{2}\)
= 0.3465 s\(^{-1}\)
\(\approxeq\) 0.347 s\(^{-1}\)
50N
40N
30N
20N
10N
Correct answer is C
No explanation has been provided for this answer.
photoelectric effect
thermionic emission
field emission
secondary emission
radioactive emission
Correct answer is B
The process by which free electrons are emitted from the surface of a metal when external heat energy is applied is called thermionic emission.