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