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.
ferrite substance
paramagnetic substance
ferromagnetic substance
diamagnetic substance
Correct answer is A
Ferrite magnets are non-conductive aferromagnetic ceramic compounds derived from iron oxides such as Haematite (Fe203) or Magnetite (Fe304) and other metal oxides such as Barium and Strontium.
Ferrite is a polycrystal, sintered material with high electrical resistivity. The high resistance of ferrite makes eddy current losses extremely low at high frequencies.
The period of a 10 kHz radio wave traveling at 108 ms−1 is--
3.0 x 10−5s
1.0 x 10−4 s
1.0 x 104s
3.0 x 104s
Correct answer is B
The relation between period and frequency is that one is the inverse of the other.
By definition:
Frequency = 1/period.
or
period = 1/frequency → 1/ 10,000
period = 0.0001 or 1.0 x 10−4 s
make the deflection of the needle proportional to the current
increase the sensitivity of the galvanometer
decrease the magnetic flux produced by the magnet
make the permanent magnet stronger
Correct answer is B
Sensitivity of a galvanometer increases when number of turns, area of coil and magnetic field increase
The power of the lens is +2.5D. What is the radius of the curvature?
2.5 cm
25.0 cm
40.0 cm
80.0 cm
Correct answer is D
The power of a lens is defined as the reciprocal of its focal length in metres:
P = 100f → 2.5 = 100f
where P is the power in diopters and f is the focal length in metres.
2.5 * f = 100
f = 1002.5
f = 40
Where f = r2
radius of the curvature[r] = f * 2 → 40 * 2
r = 80cm