Reflection of Light — Science STD 10 — Question

The world's known coal reserves are expected to last for about:

1. 200 years.
2. 400 years.
3. 500 years.
4. 100 years.

A student used a device (X) to obtain/focus the image of a well illuminated distant building on a screen (S) as shown below in the diagram. Select the correct statement about the device (X).

After testing the eyes of a child, the optician has prescribed the following lenses for his spectacles:
Left eye: +2.00D
Right eye: +2.25D
The child is suffering from the defect of vision called:

1. Short-sightedness.
2. Long-sightedness.
3. Cataract.
4. Presbyopia.

Which of the following is a natural phenomenon which is caused by the dispersion of sunlight in the sky?

To focus the image of a nearby object on the retina of an eye:

1. The distance between eye-lens and retina is increased.
2. The distance between eye-lens and retina is decreased.
3. The thickness of eye-lens is decreased.
4. The thickness of eye-lens is increased.

The relative strength of magnetic field is show by:

A solenoid with a soft iron core is called a _____:

A ray of light passes from a medium X to another medium Y. No refraction of light occurs if the ray of light hits the boundary of medium Y at an angle of:

The heat produced by passing an electric current through a fixed resistor is proportional to the square of:

1. Magnitude of resistance of the resistor.
2. Temperature of the resistor.
3. Magnitude of current.
4. Time for which current is passed.

The maximum number of 40W tube-lights connected in a parallel which can safely be run from a 240V supply with a 5A fuse is:

1. 5
2. 15
3. 20
4. 30