The inner diameter of a test tube can be measured accurately using a?
micrometer screw gauge
pair of dividers
meter rule
pair of vernier calipers
Correct answer is D
Vernier calipers are also used to measure the internal and external diameters of a tube
If the frequency of an emitted x-ray is 1.6 x 10^{16}Hz, the accelerating potential is?
[e = 1.6 x 10^{-19}J, h = 6.63 x 10-^{34}Js]
6630.0V
663.0V
66.3V
6.6V
Correct answer is C
Given f = 1.6 x10^{16}H_{3}, h = 6.63 x 10^{-39}Js
e = 1.6 x 10^{-19}C, V = ?
V = \frac{w}{e} = \frac{hf}{e} = \frac{1.6 \times 10^{16} \times 6.63 \times 10^{34}}{1.6 \times 10^{-19}}
= 66.3V