Electricity — Science STD 10 — Question

Which of the following can be produced during the nuclear fission as well as nuclear fusion reactions?

1. Protons.
2. Deutrons.
3. Electrons.
4. Neutrons.

The mirror used by a dentist to examine the teeth of a person is:

Consider two statements A and B given below:

1. Real image is always inverted.
2. Virtual image is always erect.

Out of these two statements:

A concave mirror has a focal length of 25cm. At which of the following distance should a person hold his face from this concave mirror so that it may act as a shaving mirror?

1. 45cm
2. 20cm
3. 25cm
4. 30cm

Give reason for your choice.

In a filament type light bulb, most of the electric power consumed appears as:

1. Visible light.
2. Infra-red-rays.
3. Ultraviolet rays.
4. Fluorescent light.

Three different circuits (I, II and III) are constructed using identical batteries and resistors of R and 2R ohm. What can be said about current I in arm AB of each circuit.

Though a woman can see the distant object clearly, she cannot see the nearby objects clearly. She is suffering from the defect of vision called:

By using convex lens, a student obtained a sharp image of his class-room window grill on a screen. In which direction should he move the lens to "focus a distant tree instead of the grill?

Suppose you have focused on a screen the image of candle flame placed at the farthest end of the laboratory table using a convex lens. If your teacher suggests you to focus the parallel rays of the sun, reaching your laboratory table, on the same screen, what you are expected to do is to move the:

The energy produced by converting 1 gram mass of a nuclear fuel into energy completely is:

1. 9 × 10¹⁶J.
2. 9 × 10¹⁴J.
3. 9 × 10¹⁵J.
4. 9 × 10¹³J.