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.
Birds can perch safely on overhead electric power cables without being electrocuted because
birds can withstand high p.d. of the electric power cables
any accumulated charge on the birds is quickly dissipated
the feet of the birds are well insulated
the current is a.c. and has particular direction
there is no p.d between the birds and the cables
Correct answer is C
No explanation has been provided for this answer.
Calculate the resistance of the filament of a lamp rates 240 V, 40 W
240Ω
360Ω
720Ω
1440Ω
2880Ω
Correct answer is D
R = V2/P = 2402/40 = 1440Ω
0.0009Ω/π
100Ω
1030Ω
400Ω
2500Ω
Correct answer is D
Given Data: Frequency (F) = \(\frac{500}{π}\) , Inductance (L) = 0.9H, Capacitance (C) = \(2 \times 10^{-6}\)
Total circuit reactance = Inductive reactance ( X\(_L\) ) - Capacitive reactance ( X\(_C\) )
when ( X\(_L\) ) > ( X\(_C\) )
Inductive reactance ( X\(_L\) ) = 2πFL = 2 \(\times\) π \(\times\) \(\frac{500}{π}\) \(\times\) 0.9 = 900Ω
Capacitive reactance ( X\(_C\) ) = \(\frac{1}{2πFC}\) = \(\frac{1}{2 \times π \times 500/π \times 2 \times 10^{-6}}\)
= \(\frac{1}{2 \times 10^{-3}}\) = \(\frac{1}{0.002}\)
= 500Ω
Total circuit reactance = ( X\(_L\) ) - ( X\(_C\) ) = (900 - 500)Ω
=400Ω
8.00 x 106NC-1
4.00 x 106NC-1
4.00 x 10-4NC-1
2.00 x 10-4NC-1
2.50 x 10-1NC-1
Correct answer is B
F = qE; E = F/q = 40/(1.0 x 10-5) = 4.0 x 106
What is the value of R when G shows no deflection in the circuit illustrated above?
80Ω
75Ω
45Ω
20Ω
10Ω
Correct answer is D
R/30 = 100/150R = 20Ω