Light Energy — PHYSICS STD 8 — Question

Write the factors that determine whether a solid will float or sink in a liquid.

An iron washer is heated. State the effect on its external.

Write the correct statement :
When we speak in front of a microphone, the electric energy changes into sound energy.

Superficial expansion

Loudness

Yashika was given an electroscope with its gold leaves diverged. What do the diverged leaves indicate? She was also given a rod which she did not know was charged or not. Yashika touched the rod to the cap of the electroscope to find that the divergence of the gold leaves decreased. What should she infer about the charge status of the rod?

Sleepers are used below the rails.

A boy does a work of 800 J is dragging a sack of rice through a distance of 10 m. What is the magnitude of force applied by the boy?

On the basis of electron transfer, explain, why an ebonite rod gets negatively charged on rubbing with cat’s skin.

Write the correct statement :
When a flat sheet of copper is heated the increase in its area is called cubical expansion.