The Human Eyes And The Colourful World — Science STD 10 — Question

If three resistors 2 ohm, 3 ohm and 4 ohm are connected in series, then effective resistance in a circuit will be _______ ohm:

Using the circuit given below, state which of the following statement is correct?
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1. When S₁ and S₂ are closed, lamps A and B are lit.₂2
2. With S₁ open and S₂ closed, A is lit and B is not lit.
3. With S₂ open and S₁ closed A and B are lit.
4. With S₁ closed and S₂ open, lamp A remains lit even if lamp B gets fused.

In an electrical circuit three incandescent bulbs A, B and C of rating 40W, 60W and 100W respectively are connected in parallel to an electric source of the following is likely to happen regarding brightness?

The speed of light in air is:

The steps involved in observing a slide under a microscope are given below. They may not be in proper sequence.

1. 
   Focus the object under high power of the microscope.
2. 
   Place the slide on the stage of the microscope.
3. 
   Arrange the mirror to reflect maximum light to the slide.
4. 
   Focus the object under low power of the microscope.

The proper sequence of steps is:

Circuit Breaker Device which can be used in place of fuse in domestic electric wiring is called:

1. CBD.
2. DCB.
3. MCD.
4. MCB.

A beam of light is incident through the holes on side A and emerges out of the holes on the other face of the box as shown in the Figure. Which of the following could be inside the box?

The frequency of alternating current (a.c.) supply in India is:

For the refraction of a ray of light through a glass prism, the path of a ray of light is shown below:

The angle of incidence, the angle of emergence and the angle of deviation respectively have been represented by

In order to obtain a magnification of, −1.5 with a concave mirror of focal length 16cm, the object will have to be placed at a distance.