Heat — Physics STD 10 — Question

The rearview mirror of a motorbike starts vibrating violently at some particular speed of the motorbike, what could be done to stop the violent vibrations.

What change do you expect in the characteristics of a musical sound if
(i) Its frequency is increased,
(ii) Its amplitude is increased?

A light ray in passing from water to a medium
(a) speeds up
(b) slows down. In each case, give one example of the medium.

What do you mean by electron emission?

A cell is used to send current to an external circuit. (a) How does the voltage across its terminals compare with its e.m.f? (b) under what condition is the e.m.f of a cell equal to its terminal
voltage?

What do you understand by the following terms
(a) Couple (b) Arm of couple (c) Moment of couple

State any two ways of increasing the frequency of vibration of a stretched string.

A fuse is rated 8 A'. Can it be used with an electrical appliance of rating 5 kW, 200 V?

A body is acted upon by two forces, each of magnitude F, but in opposite directions. State the effect of the forces when
(a) Both forces act at the same point of the body.
(b) The two forces act at two different points of the body at a separation d.