Magnetic Effects of Electric Current — Science STD 10 — Question

In many applications, solar cells are connected to rechargeable batteries. Why is this so?

Compare the power used in the 2 Ω resistor in each of the following circuits:

1. A 6 V battery in series with 1 Ω and 2 Ω resistors.
2. A 4 V battery in parallel with 12 Ω and 2 Ω resistors.

Explain why, when it is getting dark at night, it is impossible to make out the colour of cars on the road.

Draw a circuit diagram to show how two 4V electric lamps can be lit brightly from two 2V cells.

Why does a beam of light when it enters glass at an angle? Why does it not bend if it inters the glass at right angles?

While studying the dependence of potential difference (V) across a resistor on the current (I) passing through it, in order to determine the resistance of the resistor, a student took 5 readings for different values of current and plotted a graph between V and I. He got a straight line graph passing through the origin. What does the straight line signify? Write the method of determining the resistance of the resister using this graph.

State two hazards associated with the use of electricity.

What do you understand by the “resistivity” of a substance?

What is Maxwell’s corkscrew rule? For what purpose is it used?

A person needs a lens of power –5.5 dioptres for correcting his distant vision. For correcting his near vision he needs a lens of power +1.5 dioptre. What is the focal length of the lens required for correcting (i) distant vision, and (ii) near vision?