NUST NET Physics chapter 7: Physics · Solids and electronics MCQs with answers
By Team Megalecture · Updated 4 Nov 2026
28 exam-style questions on Physics · Solids and electronics, each with the answer and a short explanation. Ten of them are below to try. The chapter test draws ten fresh questions each time and is marked the moment you finish, with your score by topic.
Ten Physics · Solids and electronics questions with answers
Try each one, then open the answer. These ten stay the same; the test draws new ones every time.
1. In a p-type semiconductor, the majority charge carriers and the overall charge of the material are
A
holes; positively charged
B
holes; electrically neutral
C
electrons; electrically neutral
D
electrons; negatively charged
Show answer
Answer: B. Trivalent doping gives an excess of holes, but each acceptor atom is itself neutral, so the crystal as a whole carries no net charge.
2. A wire of Young's modulus 1.0 × 1011 Pa is under a tensile stress of 5.0 × 107 Pa. Its tensile strain is
A
2.0 × 103
B
5.0 × 10−4
C
5.0 × 1018
D
5.0 × 10−2
Show answer
Answer: B. Strain = stress/Y = 5.0 × 107 ÷ 1.0 × 1011 = 5.0 × 10−4 (0.05%); it has no unit. 2.0 × 103 divides the wrong way round, and 5.0 × 10−2 writes 0.05% as if it were 0.05.
3. A wire 2.0 m long with a cross-sectional area of 1.0 mm2 has Young's modulus 2.0 × 1011 Pa. A load of 100 N stretches it by
A
0.50 mm
B
2.0 mm
C
1.0 × 10−3 mm
D
1.0 mm
Show answer
Answer: D. Extension = FL/(AY) = 100 × 2.0/(1.0 × 10−6 × 2.0 × 1011) = 1.0 × 10−3 m = 1.0 mm. Taking 1.0 mm2 as 1.0 × 10−3 m2 instead of 1.0 × 10−6 m2 gives 1.0 × 10−3 mm.
4. A wire is stretched within its elastic limit so that the stress in it is 3.0 × 108 Pa and the strain is 2.0 × 10−3. The elastic energy stored per unit volume of the wire is
A
6.0 × 105 J m−3
B
3.0 × 105 J m−3
C
1.5 × 1011 J m−3
D
3.0 × 10−5 J m−3
Show answer
Answer: B. Energy per unit volume = ½ × stress × strain = ½ × 3.0 × 108 × 2.0 × 10−3 = 3.0 × 105 J m−3. Leaving out the ½ gives 6.0 × 105; 1.5 × 1011 is stress ÷ strain, the Young's modulus in Pa, not an energy.
5. In a transistor the emitter current is 10.0 mA and the collector current is 9.8 mA. Its current gain β is
A
0.98
B
50
C
1.02
D
49
Show answer
Answer: D. IB = IE − IC = 0.2 mA, so β = IC/IB = 9.8/0.2 = 49. 0.98 is α = IC/IE, a different ratio.
6. To make an n-type semiconductor, pure silicon is doped with a small amount of
A
boron
B
aluminium
C
phosphorus
D
gallium
Show answer
Answer: C. Phosphorus is pentavalent: four of its valence electrons form bonds and the fifth is free to conduct, giving n-type material. Boron, aluminium and gallium are trivalent and give p-type material.
7. Glass is an example of
A
a crystalline solid
B
a polymeric solid
C
a ductile solid
D
an amorphous solid
Show answer
Answer: D. Glass has no regular long-range arrangement of its atoms and no sharp melting point; it softens gradually. Such solids are called amorphous (glassy) solids.
8. The core of a transformer is made of a soft magnetic material such as soft iron because such a material has
A
a hysteresis loop of small area, so little energy is lost in each cycle
B
a hysteresis loop of large area, so it keeps its magnetism
C
a very high electrical resistance
D
no magnetic domains
Show answer
Answer: A. Soft iron is easily magnetised and demagnetised; its narrow hysteresis loop means little energy is wasted as heat in each cycle. Materials with wide loops, such as steel, suit permanent magnets.
9. Wires A and B are made of the same material. B is twice as long as A and has twice its diameter. When the same force stretches each, the ratio of the extension of B to that of A is
A
1 : 2
B
2 : 1
C
1 : 1
D
1 : 4
Show answer
Answer: A. Extension ΔL = FL/(AY) ∝ L/d2. For B this is 2/22 = ½ of A's extension. Using the diameter instead of the area (2/2) gives 1 : 1.
10. A force of 50 N stretches a wire by 2.0 mm within its elastic limit. The elastic energy stored in the wire is
A
0.10 J
B
0.050 J
C
50 J
D
0.025 J
Show answer
Answer: B. Energy = ½Fx = ½ × 50 × 2.0 × 10−3 = 0.050 J. Leaving out the ½ gives 0.10 J; not converting mm to m gives 50 J.
Chapter test. Ten questions from Physics · Solids and electronics, drawn fresh each time, about ten minutes.
Practice mode. The right answer and the explanation after every question, with no clock. Exam mode keeps the marks until the end and runs a timer.
Hints. One tap for a nudge, a second to remove two wrong options.
My mistakes. Every question you get wrong is kept, and leaves the list once you get it right.
Physics · Solids and electronics: questions students ask
How many Physics · Solids and electronics MCQs are there?
28, each with the answer and a short explanation, across 2 topics: Physics of solids, Electronics. Every chapter test draws ten of them, so you can take it many times.
Is the NUST NET Physics chapter 7 test free?
Yes. The test, the answers and the explanations are free and need no sign-up. Sign in only if you want your scores kept across devices.
How is the chapter test marked?
The moment you press Finish: your score, the right answer and an explanation for every question, and the ones you got wrong saved in My mistakes to retry.
Can I read the explanations in Urdu?
Yes. In practice mode and on your results you can switch the explanations to Urdu.
