Electricity and Circuits quiz

The metal cap of a cell is its:

Which of the following is a conductor?

Which of the following is an insulator?

A bulb glows when the circuit is:

The thin wire inside a bulb that glows is called the:

A fused bulb has a:

Which device is used to break or complete a circuit?

In a torch, cells are placed so that:

The covering on electric wires is made of:

Which of these is a source of electricity in a torch?

Why should we never touch a switch with wet hands? (2 marks)

Name two materials used for making electric wires and give a reason. (2 marks)

What is the difference between an open circuit and a closed circuit? (2 marks)

Name two devices that use electric cells. (2 marks)

Why does a bulb not glow when the filament is broken? (2 marks)

Why do electricians use screwdrivers with plastic handles? (2 marks)

Is air a conductor or an insulator? Give evidence from a switch. (2 marks)

How does a switch made of a safety pin and drawing pins work? (2 marks)

Why is it dangerous to fly kites near electric wires? (2 marks)

Can the electricity supplied to our homes be used directly for activities in the classroom? Why not? (2 marks)

A student tested 12 objects with a tester. The bulb glowed for 5 objects. How many insulators did she find? What fraction of the objects were conductors? (3 marks)

A shop sells cells at Rs 15 each. A torch needs 3 cells and a toy car needs 4 cells. Find the cost of cells for 2 torches and 1 toy car. (3 marks)

A pair of cells in a torch lasts 30 hours. If the torch is used for 1 hour 30 minutes every night, after how many nights should the cells be replaced? (3 marks)

In a circuit, the current flows from the positive terminal through 25 cm of wire to a bulb and then through 35 cm of wire back to the negative terminal. Find the total length of wire used. If one wire is disconnected, how much of the circuit carries current? (3 marks)

A class has 30 students working in pairs. Each pair needs 1 cell, 1 bulb and 2 wires. Find the total number of cells, bulbs and wires needed. (3 marks)

Read the passage and answer the questions. During a power cut, Riya took out a torch, but it did not light up. She opened it and found the cells placed with both positive terminals touching each other. She corrected them and the torch lit up. (i) What was wrong with the arrangement? (ii) Why did the torch work after correction? (iii) Draw how the cells should be arranged. (5 marks)

Read the passage and answer the questions. An electrician came to repair a fan. He switched off the main supply, wore rubber slippers and used a tester screwdriver with a plastic handle. (i) Why did he switch off the main supply? (ii) Why did he wear rubber slippers? (iii) Why does the screwdriver have a plastic handle? (5 marks)

Read the passage and answer the questions. Ravi made a tester using a cell, a bulb and wires. When he touched the free ends to a key, the bulb glowed. When he touched them to an eraser, it did not glow. (i) Is the key a conductor or insulator? (ii) Is the eraser a conductor or insulator? (iii) Name two more objects that will make the bulb glow. (5 marks)

Read the passage and answer the questions. Meena connected a bulb to a cell with two wires. The bulb glowed at first, but after a while it stopped glowing even though the connections were tight. She replaced the cell and the bulb glowed again. (i) Why did the bulb stop glowing? (ii) What does this tell us about cells? (iii) Name a source of electricity that can be used for a long time. (5 marks)

Read the passage and answer the questions. Mohan noticed that the copper wire in his home was covered with plastic and the switch board was made of plastic. In the bathroom, the geyser switch was placed outside. (i) Why are wires covered with plastic? (ii) Why are switch boards made of plastic? (iii) Why is the geyser switch outside the bathroom? (5 marks)

Draw a labelled diagram of an electric cell and an electric bulb. Explain how they are connected to make a closed circuit and how current flows. State what happens when the circuit is broken. (6 marks)

Draw a labelled diagram of a torch showing the cells, switch, bulb and reflector. Explain how the switch completes the circuit and why the bulb glows. (6 marks)

Describe how to make a simple switch using a safety pin, drawing pins and a thermocol sheet. Draw a circuit with this switch in the on and off positions and explain each. (6 marks)

Describe an activity to classify objects as conductors and insulators using a tester. Draw the tester and make a list of ten objects with your observations. (6 marks)

List six safety rules for using electricity at home and school, and explain the reason behind each. Draw a sketch of a correctly insulated plug and wire. (6 marks)