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.
The speed of fast-moving neutrons in a nuclear reactor can be reduced by using?
graphite rods
concrete shield
iron rods
boron rods
Correct answer is A
Moderation is the process of the reduction of the initial high speed (high kinetic energy) of the free neutron.
Since energy is conserved, this reduction of the neutron speed takes place by transfer of energy to a material called a moderator.
There are several different types of moderating materials, and each have places where they are used more effectively.
Typically-used moderator materials include heavy water, light water, and graphite.
0.200A
0.070A
0.050A
0.008A
Correct answer is D
Given Data: L = 10, V = 50, F = 100, I = ?
Inductive Reactance [X\(_L\)] = 2\(\pi\)FL → 2 * 3.14 * 100 * 10
X\(_L\) = 6,280
Current[I] = \(\frac{V}{X_L}\) → \(\frac{50}{6280}\)
I = 0.0079
≈ 0.008A
2.5\(\Omega\)
5.0\(\Omega\)
8.0\(\Omega\)
10.0\(\Omega\)
Correct answer is B
r = resistance of the galvanometer
l = current through galvanometer = 20mA or 0.02A
V1 = p.d across the galvanometer = I X r = 0.02 X r
: V1 = 0.02r
V2 = p.d across the multiplier = 8 - 0.02r
R = resistance of the multiplier = 395Ω
where R = \(\frac{V}{I}\)
--> 395 = \(\frac{8−0.02r}{0.02}\)
CROSS MULTIPLY
8−0.02r = 395 * 0.02
8−0.02r = 7.9
--> 0.02r = 8 - 7.9
∴ r = \(\frac{0.1}{0.02}\)
= 5Ω
Which of the following statements about electric potential energy is not correct?
The electric potential energy of a positively charged particle increases when it moves to a point of higher potential
The electric potential energy of a negatively charged particle increases when it moves to a point of lower potential
The electric potential energy of a positively charged particle decreases when it moves to a point of higher potential
The work done in taking a charged particle around a closed path in an electric field is zero.
Correct answer is B
The potential energy for a positive charge increases when it moves against an electric field
And decreases when it moves with the electric field;
The opposite is true for a negative charge. Unless the unit charge crosses a changing magnetic field, its potential at any given point does not depend on the path taken.
0.90A
0.39A
0.30A
0.01A
Correct answer is C
Given Data: Emf = 1v, r = 2 ohms, R = 3 ohms, I = ?
3 resistance in parallel = \(\frac{1}{r_1}\) + \(\frac{1}{r_2}\) + \(\frac{1}{r_3}\)
\(\frac{1}{r_T}\)= \(\frac{1}{2}\) + \(\frac{1}{2}\) + \(\frac{1}{2}\)
\(\frac{1}{r_T}\) = \(\frac{1+1+1}{2}\)
\(\frac{1}{r_T}\) = \(\frac{3}{2}\)
cross multiply
r\(_T\) = \(\frac{2}{3}\) or 0.67
E = I(R+r)
1 = I(3+0.67)
1 = I(3.67)
1 ÷ 3.67 = I
0.27 = I
: I ≈ 0.30A