Energy — PHYSICS STD 7 — Question

Why are gaps left between successive rails on a railway track ?

Why are the telephone of telegraph wires laid in summer kept slightly loose, while in winter they are kept tight?

Write a short note on some devices that are used to measure the volume of liquids.

Define non-luminous object and give examples.

There are two children riding a bicycle with the same speed on a straight road. Explain whether these children are at rest or in motion.

Differentiate between transverse and longitudinal waves.

State two factors on which the potential energy of a body at a certain height above the ground depends.

Why is the word ‘AMBULANCE’ printed laterally inverted on an ambulance van?

In which arrangement are the appliances connected in the electric circuit of our homes, Series or Parallel ? Give one reason for your answer.