Advertisements
Advertisements
Question
In case of a fire, before the firemen use the water hoses, they shut off the main electrical supply for the area. Explain why they do this.
Solution
Because the water the fireman uses during a fire is not pure and contains salts, which makes it a good conductor of electricity, the fireman turns off the main electricity supply of that area before using the water hoses (pipes). The fireman does this to protect himself and others from short circuits. Otherwise, he may get an electric shock due to it.
APPEARS IN
RELATED QUESTIONS
Most liquids that conduct electricity are solutions of ________, _______ and ________.
When the free ends of a tester are dipped into a solution, the magnetic needle shows deflection. Can you explain the reason?
The bulb does not glow in the setup shown in figure list the possible reasons. Explain your answer.
A tester is used to check the conduction of electricity through two liquids, labelled A and B. It is found that the bulb of the tester glows brightly for liquid A while it glows very dimly for liquid B. You would conclude that ______.
Does pure water conduct electricity? If not, what can we do to make it conducting?
A child staying in a coastal region tests the drinking water and also the seawater with his tester. He finds that the compass needle deflects more in the case of seawater. Can you explain the reason?
Observe the circuit given in the figure.
Boojho set up this circuit for purification of copper. What will be the nature of – (a) plate A (b) plate B (c) and the solution.
Explain the process of purification.
Observe the following circuit given in the figure.
Current does not flow in the circuit, if there is a gap between the two wires. Does it indicate that air is a poor conductor of electricity? Does air never conduct electricity? Explain.
Boojho made the circuit as shown in the figure. He wanted to observe what happens when an electric current is passed through water. But he forgot to add a few drops of lemon juice to water. Will it make any difference to his observations? Explain.
Observing that the bulb does not glow in the circuit shown in Fig. (A) Boojho changed the circuit as shown in Fig. (B). He observed deflection in the magnetic compass.
 |
 |
| A | B |
- What does the deflection in magnetic compass indicate?
- Why did the bulb not glow in Fig. (A)?
- What would be the effect of increase in the number of turns in the coil wound around the magnetic compass in Fig. (B)?
- What will be observed if the number of cells are increased in the circuit shown in Fig. (B)?
