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.
An isotope has an initial activity of 120 Bq. 6 days later its activity is 15 Bq. The half-life is?
3 days
2 days
1 day
4 days
Correct answer is B
The equation that establishes a relationship between the amount left undecayed,
A, the initial amount, A0, and the number of half-lives that pass in a period of time t looks like this:
\(\frac{1}{2^n} * A_0 = A\)
\(\frac{1}{2^n} * 120 = 15\)
\(\frac{1}{2^n}\) = \(\frac{15}{120}\)
\(\frac{1}{2^n}\) = \(\frac{1}{8}\)
\(\frac{1}{2^n}\) = \(\frac{1}{2^3}\)
\(2^n = 2^3\)
n = 3
:6days ÷ 3 = 2days
Which of the following liquid is a poor conductor of electricity?
Distilled water
Tap water
Sea water
Drinking water
Correct answer is A
Distilled water is free of salts and is a poor conductor of electricity.
4.00 V
2.20 V
0.15 V
8.00 V
Correct answer is B
Lost voltage = I x R
= 4 x 0.55
= 2.2V
formation of hydrogen bubbles on the electrode
increase in the resistance of the cell
local action
polarization
Correct answer is C
If the zinc used in the simple cell is of the impure commercial variety bubbles of hydrogen will be seen coming off the zinc. This is called local action
\(\gamma\) = \(\alpha ^{-3}\)
\(\gamma\) = \(\alpha\)
3\(\alpha\)
\(\gamma\) = \(\alpha ^{3}\)
Correct answer is C
volumetric expansion (γ) = 3x Linear expansion