Tester

Q. In the tester, LED bulb is used in place of a normal bulb because LED bulb needs ____ electric current in comparison.

1. less

2. equal

3. more

4. alternate

Q.

Question 5
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
(i) liquid A is a better conductor than liquid B.
(ii) liquid B is a better conductor than liquid A.
(iii) both liquids are equally conducting.
(iv) conducting properties of liquid cannot be compared in this manner.

Q.

How is distilled water different from tap water in terms of electrical conductivity? Explain the reason for this difference. [2 MARKS]

Q.

Materials which allow electric current to pass through them are called

1. Insulators

2. Conductors

3. Electrode

4. None of these

Q. How can you identify conductors and insulators using an electroscope?

Q.

What is electric discharged

Q. Does milk conduct electricity? (I want a definite answer).

Q.

Name a device which glows even when a weak electric current passes through it.

Q.

Most liquids that conduct electricity are solutions of ___________ , ____________ and ___________.

Q.

What is the advantage of using LED in testing the electrical conductivity of liquids?

Q.

Question 2

Boojho and Paheli performed experiments taking similar bulbs and cells but two different solutions A and B as shown in Fig.



They found that the bulb in the setup A glows more brightly as compared to that of the setup B. You would conclude that
(a) Higher current is flowing through the circuit in setup A.
(b) Higher current is flowing through the circuit in setup B.
(c) Equal current is flowing through both the circuits.
(d) The current flowing through the circuits in the two setups cannot be compared in this manner.

Q.

Using the “conduction tester” on an object it was found that the bulb begins to glow. Is that object a conductor or an insulator? Explain.

Q.

__ glows even when a weak electric current flows through it.

Q. What physical changes may one observe upon passage of an electric current through a conducting solution?

Q. Question 8 (iii)
Fill in the blanks.
(c) Small amount of a mineral salt present naturally in water makes it a ___ of electricity.

Q. The process of electric discharge can occur:

1. Between two clouds
2. Between clouds and the earth
3. All the above
4. Between three clouds

Q. Crushing of a chalk piece to get powdered chalk is an example of physical change.

1. False
2. True

Q.

The device which can be used to detect very small current flowing in an electric circuit is :
(a) LEAD
(b) dB
(c) MCB
(d) LED

Q.

What happens when air is ionized?

Q.

A tester is used to check the conduction of electricity through two liquids, labeled 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

1. liquid A is a better conductor than liquid B.

2. liquid B is a better conductor than liquid A.

3. both liquids are equally conducting.

4. conducting properties of liquid cannot be compared in this manner.

Q.

A puppy was trapped by a current-carrying wire and was barking for help, a little boy couldnt stop himself and rushed for help and tried to save the dog by his naked hands but was caught himself. A man passing nearby took a wooden stick and saved both of them. Why did he use a wooden stick?

Q. Which of the following cannot be used as an electrolyte?

1. Salt water
2. Copper sulphate solution
3. Acetic acid solution
4. Distilled water

Q.

Question 5
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
(i) liquid A is a better conductor than liquid B.
(ii) liquid B is a better conductor than liquid A.
(iii) both liquids are equally conducting.
(iv) conducting properties of liquid cannot be compared in this manner.

Q.

Is it safe to touch a capacitor?

Q. While testing an LED, it is advised not to close the circuit for a long time because the ___________.

1. LED can get damaged
2. wires will burn up
3. cells of the battery will drain very quickly
4. circuit gets overloaded

Q.

A tester is made with the two terminals of a battery connected to separate wires, each with one end free. A light bulb is also connected as a part of the circuit. Now an object is used to connect the free ends, and it is observed that the light bulb does not glow, in other words, there is no electricity flowing. Which of the following could be that object?

1. Copper wire

2. A wooden stick

3. A gold strip

4. An iron strip

Q.

A tester is used to check the conductivity of an unknown solution of water. What can be concluded, if the bulb of the tester glows brightly?

1. The solution consists of impurities.

2. The solution is transparent.

3. The solution consists of ions.

4. The solution is opaque.

Q.

Write the full form of LED.

Q.

You are using a tester with a light bulb to conduct an experiment to find out if a liquid is a conductor of electricity. But you observe that one of the liquids which are supposed to be a conductor according to your textbook is not causing the light bulb to glow, even though you have checked that all the connections are fine, and the battery and bulb are in working condition. What could be the possible reason for this?

Q.

Which of the following serves as an indicator in an electrical tester?

1. Bulb
2. Fuse wire
3. Cell
4. Switch