Electricity — Science STD 10 — Question

Solar cells are used to provide the electric current to charge the batteries of a car driven by an electric motor. Describe the energy changes which take place.

How has the traditional use of energy of flowing water been modified for our convenience?

An object is moved closer to an eye. What changes must take place in the eye in order to keep the image in sharp focus?

Three V-I graphs are drawn individually for two resistors and their series combination. out of A, B, C which one represents the graph for series combination of the other two? Give reason for your answer.

How many electrons are flowing per second past a point in a circuit in which there is a current of 5 amp?

In the given circuit, connect a nichrome wire of length 'L' between points X and Y and note the ammeter reading.

1. When this experiment is repeated by inserting another nichrome wire of the same thickness but twice the length (2L), what changes are observed in the ammeter reading?

2. State the changes that are observed in the ammeter reading if we double the area of cross-section without changing the length in the above experiment. Justify your answer

in both the cases.

Calculate the resistance of an electric bulb which allows a 10 A current when connected to a 220 V power source?

A heating coil has a resistance of 200Ω. At what rate will heat be produced in it when a current of 2.5A flows through it?

The atoms of copper contain electrons and the atoms of rubber also contain electrons. Then why does copper conduct electricity but rubber does not conduct electricity?

A person walking in a dark corridor enters into a brightly lit room:

1. State the effect on the pupil of the eye.
2. How does this affect the amount of light entering the eye?