Light — Physics STD 10 — Question

Amphitheaters and auditorium walls are fitted with ________ to avoid the echoing of sound.

The point on the principal axis of a convex lens, such that rays of light starting from it on passing through the lens move parallel to the principal axis is called:

The present of magnetic field at a point can be detected by :

When a charge is moving in a magnetic field, in a direction other than the direction of magnetic field it experiences a force. This force is referred as ____________ .

The electric current flows through a liquid when:

A rectangular thin plate of dimension 3 m x 4 m is balanced on the fulcrum as shown below Find the resultant moment of force?

Assertion (A): Strings of different thicknesses are provided on a stringed instrument.
Reason (A): Notes of different frequences can be obtained by producing vibrations in different strings having different thicknesses.

Read the case and answer the following questions:
Case 1: 2 A current is flowing through a copper wire X of length 2 km and radius 2 cm.
Case 2: 4 A current is flowing through a copper wire Y of length 1 km and radius 2 cm.
Case 3: A copper wire Z carrying P amount of current by having potential difference of 16 V and resistance of 2 ohm.
Answer the following question?
(iii) Which wire can be used for wiring a circular ring of radius 318 m ?

In a house 2 fans of 60 W and 2 bulbs of 40 W each are used simultaneously the current drawn from 110 V will be _____________ .

For effective reflection of sound waves, the condition of the surface should be: