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Lens used to remove long-sightedness (hypermetropia) is

A microphone converts :

(a) electric energy into sound energy in ordinary telephone

(b) microwave energy into sound energy in a mobile phone

(c) sound energy into mechanical energy in a stereo system

(d) sound energy into electrical energy in public address system

A boy walks from his classroom to the bookshop along a straight corridor towards North. He covers a distance of 20 m is 25 seconds to reach the bookshop. After buying a book, he travels the same distance at the same time to reach back in the classroom. Find (a) average speed, and (b) average velocity, of the boy.

Which one of the following correctly represents a food chain?

In above 3 figures, the arrows indicate the direction of force and magnitude of force is written above/below the arrows.

Which box is experiencing balanced force?

State the effect of global warming in coastal regions.

If the moon doesn't fall because of the principle that at every point the moon goes to it is pulled up by other points of the earth so why don't we humans also get attracted to earth in such a way that we move in circular motion?

A man pushes on a wall out of frustration with a force of magnitude 30 N. What magnitude of force does the wall exert on the man?

1. Defne conduction?
2. Ice is kept in a double walled container why?
3. Differentiate convection and radiation

What does the weak nuclear force in the atom do?

why is glass or china ware is packed with straw?

Which of the following contribute to the reason behind the origin of surface tension?

Value of (10.5)³

A rigid body is cut in to two pieces by a plane containing the center of mass of the body. Regarding the masses of the two pieces formed, which of the following is correct?

A piece of pure gold (density = 19.3 gcm^-3 ) is suspected to be hollow from inside. It weighs 77.2 g in air and 71.2 g in water. The volume of the hollow portion in gold will be

A radio transmitter sends a radio wave from the top of a 50-foot tower. The wave is represented by the graph shown at the right. What is the equation of this radio wave?

A boy standing at the top of a tower, which is 20m high, drops a stone. Assume g = 10$\frac{m}{s^2}$, find the velocity with which the stone hits the ground.

Viscosity of liquids ___ with an increase in temperature and the viscosity of gases ___ with an increase in temperature.

Choose the applications of ultrasonic sound:

A car of mass 1000 kg is moving with a velocity of $v=10m{s}^{-1}$ . If the velocity-time graph for this car is a horizontal line parallel to the time axis, then the velocity of car at the end of 25 s will be :

(a) $25m{s}^{-1}$

(b) $40m{s}^{-1}$

(c) $10m{s}^{-1}$

(d) $250m{s}^{-1}$

Give reason for the following :

The force of gravitation between two cricket balls is extremely small but that between a cricket ball and the earth is extremely large.

Which of the following constitute a food chain:

Define motion. What do you understand by the terms 'uniform motion' and 'non-uniform motion'? Explain with examples.

A doctor advised to use icepad on forehead to bring fever down instead of using water at 100 degree c.why?

Choose the correct option.
$\begin{array}{ccc}1.& \text{Overtone}& \text{i}.\text{frequencies that are integral multiple of fundamental frequency}\\ 2.& \text{Note}& \text{ii}.\text{Sound of single frequency}\\ 3.& \text{Tone}& \text{iii}.\text{Sound of multiple frequencies}\\ 4.& \text{Harmonics}& \text{iv}.\text{Higher frequencies other than fundamental frequency}\end{array}$

Why does the liquid rise in a syringe when its piston is pulled up?

In what direction and at what point does the buoyant force on a body due to a liquid, act ?

Two stones ,having masses in the ratio of 3:2 are dropped from the heights in the ratio of 4:9 the ratio of magnitudes of their linear momenta just before reaching the ground is (neglect air resistance)

Find time t, when the particle whose v - t graph is as shown, is back to its starting position.

Sir/Mam following is my question :

In oil tankers some space is left at the top while filling them. Explain why.

Pls help me solve this question.

Thnx

A body performs an accelerated motion, with uniform speed. The motion of body is

Which instrument can be used to show that magnetic field exists around a wire carrying current? Why does a compass needle get deflected when brought near a bar magnet? [3 MARKS]

A car initially at rest starts moving with uniform acceleration of $10m{s}^{-2}$ for $10seconds$. What is the total distance covered by the car?

Find the free-fall acceleration of an object on the surface of the moon, if the radius of the moon and its mass are $1740km$ and $7.4\times {10}^{22}$ kg respectively. Take $G=6.67\times {10}^{-11}N{m}^{2}k{g}^{-2}$

The acceleration of the above velocity-time graph is:

A small magnet is suspended by a silk thread from a rigid support such that the magnet can freely swing. How will it rest?

When the eye is looking at a distant object, then the focal length of the eye:

An average force of 100N acts on a body for 1s. What is the impulse due to the force?

A helicopter is moving at a speed of 56 km/h. One second later it is moving at 58 km/h. What is its acceleration?

A swimming pool is 90 m long. Rekha covers 180 m in one minute by swimming from one end to the other and back along the same straigh path. Find the average speed and average velocity of Rekha.