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 number of holes in an intrinsic semiconductor
is not equal to the number of free electrons
is greater than the number of free electrons
is equal to the number of free electrons
is less than the number of free electrons
Correct answer is C
An intrinsic semiconductor, also called an undoped semiconductor, is a pure semiconductor. In intrinsic semiconductors the number of excited electrons and the number of holes are equal: n = p
The half life of a radioactive material is 12 days. Calculate the decay constant.
0.8663 \(day^{-1}\)
0.04331 \(day^{-1}\)
0.17325 \(day^{-1}\)
0.05775 \(day^{-1}\)
Correct answer is D
\(T_ {^1/_2}\) = 12 days ;V=?
\(T_ {^1/_2}\) = \(\frac{0.693}{γ}\)
⇒γ ⇒\(\frac{0.693}{t_{^1/_2}}\)
⇒γ =\(\frac{0.693}{12}\)
⇒γ= 0.05775 \(day^{-1}\)
650
900
800
250
Correct answer is A
We first find the lorry's initial velocity
a = \(4ms^-2\), s= 250m, t= 10, u=?
⇒ ut + \(\frac{1}{2}×4×(10^2)
⇒250= 10u + 200
⇒ 250-200 = 10u
⇒ 50 = 10u
⇒U =\frac{50}{10}\) = \(5ms^-1\)
For the next 10s, we set t=20s
= s = (5 × 20) + \(\frac{1}{2}×4×{20^2}\)
= s = 100 + 800
⇒ 900 m
;Distance covered:900-250 =650m
18.0V
12.0V
16.0V
20.0V
Correct answer is D
ε = 24.0 V, r=1Ω, R=5.0Ω
terminal p·d = ?
ε = IR+Ir = I(R+r)
⇒ IR+Ir = I(R+r)
⇒ I = \(\frac{24}{5+1}\)
⇒ I =\(\frac{24}{6}\)
⇒ I = 4 A
terminal p·d = 4 × 5
terminal p·d = 20.0 V
422.7
220.14
464.53
321.74
Correct answer is A
h=32·8m, p= \(1×10^3kgm^-3\)
g=9·8 \(ms^-2\) , \(P_a\)=101·3KPa
\(P_T\)= ?
P=hpg
⇒\(32·8×1×10^3 × 9·8\)=321440 \(P_a\)
⇒321·44KPa
⇒ \(P_T\) =321.44+101.3
;\(P_T\)=422·7KPa