Get the simplified Class 7 Science Extra Questions and Class 7th Curiosity Chapter 3 Electricity Circuits and Their Important Extra Question Answer with complete explanation.
Class 7 Science Chapter 3 Electricity Circuits and Their Extra Questions
Class 7 Science Chapter 3 Extra Questions on Electricity Circuits and Their
Electricity Circuits and Their Class 7 Very Short Question Answer
Question 1.
Name the type of marks for which we should look at an electrical appliance before buying?
Answer:
ISI (Indian Standard Institution Mark)
Question 2.
Unscramble the following words
(i) TBTAYER
(ii) SFEU
(iii) HTRCO
(iv) HICWTS
Answer:
(i) BATTERY
(ii) FUSE
(iii) TORCH
(iv) SWITCH
Question 3.
Paheli wanted to glow a torch bulb using a cell. She could not get connecting wires instead she got two strips of aluminium foil. Will she succeed? Explain how?
Answer:
Yes, she will succeed because aluminium is a good conductor of electricity, so it will complete the electrical circuit and bulb will glow.
Question 4.
How many terminals does an electric cell have?
Answer:
An electric cell has two terminals – one positive and one negative.
Question 5.
What happens when the electric cells in a torch are not placed in the correct order?
Answer:
If electric cells are not placed in the correct order, the torch will not work and the lamp will not glow because the circuit will not be completed.
Question 6.
What is the name of the thin wire that glows inside an electric lamp?
Answer:
The thin wire is called the filament.
Question 7.
Which terminal of an electric cell is usually connected to the metal case of the lamp?
Answer:
The positive terminal is connected to the metal case.
Question 8.
Which lamp is used in modern torches?
Answer:
LED lamps are used in modern torches.
Question 9.
What is the shape of the glass part of an incandescent lamp?
Answer:
The glass part is bulb-shaped.
Question 10.
Which terminal of LED is longer – positive or negative?
Answer:
The positive terminal of LED is longer.
Question 11.
In a simple electric circuit, the bulb lights up only when a clip is pressed. What does the clip represent?
Answer:
The clip acts as a switch.
Question 12.
A boy draws a circuit with a cell, wire, bulb and a gap in between. What is missing for the bulb to glow?
Answer:
A switch or connecting wire to complete the circuit.
Question 13.
We should use plastic gloves for operating electrical devices. Explain why.
Answer:
To avoid electric shocks, we should use plastic gloves for operating electrical devices.
Question 14.
State whether electricity can pass through glass. If not, then explain the reason.
Answer:
Electricity cannot pass through glass because it is an insulator.
Question 15.
A child tries using a wooden stick to connect a bulb in a circuit, but it doesn’t glow. What property of the stick caused this?
Answer:
It is an insulator, so it does not allow current to pass.
Question 16.
During an experiment, a copper wire made the bulb glow instantly. What role did copper play here?
Answer:
Copper acted as a conductor of electricity.
Question 17.
In a classroom model, a plastic scale was added to complete a circuit, but the lamp didn’t glow. What does this tell about plastic?
Answer:
Plastic is a poor conductor or an insulator.
Electricity Circuits and Their Class 7 Short Question Answer
Question 1.
A girl made a simple circuit using a cell, a bulb and wires. She noticed the bulb did not glow.
(i) Which part should she check first in the circuit?
Answer:
She should first check if the wires are connected properly.
(ii) How can she test if the cell is working?
Answer:
She can use the cell in another working circuit to test it.
(iii) What change in the wire connection might make the bulb glow?
Answer:
If the wires are loose or not properly connected to the bulb terminals, she should tighten the connections.
Question 2.
Meena connected a battery, bulb and a key (switch) with proper wires. When she turned the key ON, the bulb glowed. Her friend Rita used the same setup but did not include the key. Yet her bulb was glowing. Give reason.
Answer:
When wires are connected directly without a switch, the circuit remains complete. So, the bulb glows even without the key.
Question 3.
Pallavi preparing a torch in her house with her friend Radhika. But even after completing the circuit, bulb doesn’t glow Radhika adviced her to check the correct sequence of cell used.
(i) State the values reflected by Radhika here.
Answer:
Radhika has good knowledge of electrical circuit and its uses. She is also cooperative with her friend.
(ii) Explain what can be the reason behind the bulb not glowing?
Answer:
There may be the incorrect sequence of cell that is used by her.
Question 4.
In a science activity, students used two cells instead of one.
(i) How should they connect the two cells to make the bulb glow brighter?
Answer:
They should connect the positive terminal of one cell to the negative terminal of the next.
(ii) What will happen if they connect both positive terminals together?
Answer:
(ii) If both positive terminals are connected together, the current won’t flow properly and the bulb may not glow.
Question 5.
Student saw a symbol with a triangle and a line and noticed it allowed current in one direction only.
Name the component and its purpose.
Answer:
The component is an LED (Light Emitting Diode). It allows current in one direction only and glows when current flows correctly.
Question 6.
Discuss briefly that how switch works?
Answer:
A device which is used to close or open a circuit is known as switch, so when we open the switch, there exists an air gap which does not allow the current to pass through it. On the other hand, when it is closed, then there is not any existence of air gap between the wires and therefore in this way, it conducts electricity.
Question 7.
A torch is not functioning, though contact points in the torch are in working condition. What can be the possible reasons for this? Mention any three.
Answer:
The possible reasons for not functioning of torch may be
(i) The torch bulb may be fused.
(ii) The cell may be discharged.
(iii) The connecting wires may be broken up.
Question 8.
Why are electric wires made of copper and not rubber?
Answer:
Because copper is a conductor and rubber is an insulator.
Question 9.
Metals are used in electric circuits but materials like glass or paper are not. Give reason.
Answer:
Metals are conductors, they allow electric current to flow. Glass and paper are insulators, so thev block the flow of current and cannot be used in electric circuits.
Question 10.
Sita is operating an base electric wire, so that its electric iron can be used safely. Her friend Vimlesh advised her not to do so without plastic gloves.
(i) Mention the values that Vimlesh shows here.
Answer:
Vimlesh is intelligent and has good knowledge of current and its hazard.
(ii) A plastic glove is an insulator or conductor.
Answer:
A plastic glove is an insulator. It does not conduct electricity.
Electricity Circuits and Their Class 7 Long Question Answer
Question 1.
In figures A and B, shown a bulb connected to a cell in two different ways.
(i) Mention the direction of the current through the bulb in both the cases
Answer:
The direction of current will be from Q to P in A and direction of current will be from P to Q in B because direction of current is always from positive terminal to negative terminal of the cell or battery.
(ii) Will the bulb glow in both the cases?
Answer:
Yes, the bulb will glow in both the cases because to glow the bulb, we just need to complete the circuit.
(iii) Does the brightness of the glowing bulb depend on the direction of current through it?
Answer:
No, the brightness of the bulb never depends upon the direction of current passing through it.
Question 2.
(i) Pinki is using an LED light to read a book. She knows that LED lights are energy efficient. Can you explain why LED lights are better than traditional bulbs in terms of energy usage?
(ii) Boojho is holding two rods, one made of copper and the other of plastic and he places both in an electric circuit. The copper rod allows the current to pass through, while the plastic rod does not. What property do these materials show?
Answer:
(i) LED lights are more energy-efficient than traditional bulbs because they convert more electrical energy into light, while traditional bulbs waste a lot of energy in the form of heat. This makes LEDs consume less power and last longer.
(ii) The copper rod is a conductor, which allows the electric current to pass through, while the plastic rod is an insulator, which does not allow the current to pass through.
Question 3.
A torch requires 3 cells. Show the arrangement of the cells with a diagram inside the torch, so that the bulb glows.
Answer:
The arrangement of cells should be such that positive terminal of a battery touches the base of the bulb. When switched ON, the bulb will glow.
Question 4.
Paheli took a wire of length 10 cm. Boojho took a wire of 5 cm of the same material and thickness. Both of them connected the wires as shown in the figure. The current flowing in both the circuits is the same.
(i) Will the heat produced in both the cases be equal? Explain.
Answer:
The amount of heat produced in a wire depends upon the length of wire, so the amount of heat produced in both the cases will not be equal.
(ii) Will the heat produced be the same if the wires taken by them are of equal lengths but of different thickness?
Answer:
The amount of heat produced in a wire depends upon the thickness of wire, so the amount of heat produced in both the cases will not be equal.
Electricity Circuits and Their Class 7 Case Based Questions
Question 1.
The figure shows an electric circuit.
(i) What will happen, if another battery is added to the circuit?
Answer:
The bulb will glow more brighter.
(ii) What is the direction of the flow of electric current in the circuit?
Use small arrows to show the direction in the picture.
Answer:
Question 2.
Neeraj designed an electric circuit as shown below.
He filled the gap in the circuit with four different objects, one at a time.
The table shows Neeraj’s findings.
| Object used to fill in the gap | ||||
| Steel pin | Iron nail | Plastic clip | Wooden stick | |
| Did the bulb glow? | Yes | Yes | No | No |
(i) Which question can be answered through Neeraj’s activity?
Choose Yes or No for the correct response.
| Can this question be answered? | Yes or No |
| (a) Are metals good conductors of electricity? | |
| (b) Are non-metals bad conductors of electricity? | |
| (c) Do all electric circuits contain an electric bulb? |
Answer:
| Can this question be answered? | Yes or No |
| (a) Are metals good conductors of electricity? | Yes |
| (b) Are non-metals bad conductors of electricity? | Yes |
| (c) Do all electric circuits contain an electric bulb? | No |
(ii) Which safety measure must Neeraj follow during the activity?
(a) Wear an apron
(b) Wear a face mask
(c) Wear a pair of goggles
(d) Wear a pair of rubber gloves
Answer:
(d) Wear a pair of rubber gloves
(iii) Neeraj repeated the activity using the same four objects. This time the bulb did not glow for any of the four objects. What could be the most likely reason for this?
Answer:
(a) The circuit may not be properly connected.
(b) The bulb may be fused.
Electricity Circuits and Their Class 7 Skill Based Questions
Question 1.
Which of the following arrangements A,B,C and D given in figures should not be set-up? Explain, why?
Answer:
Arrangement A is not desirable and should not be set up. This will exhaust the cell very quickly as large current will flow through it.
Questions 2.
Complete the drawing shown in the figure to indicate where the free ends of the two wires should be joined to make the bulb glow.
Answer:
circuit, the positive terminal of the cell should be connected to one end of the switch and the other terminal of the bulb should be connected to the other end of the switch. The closed circuit is shown in the following figure.
Question 3.
In the circuit shown in figure, when the switch is moved to ON position. What will happen to the bulbs A, B and C? Will all the bulbs glow with equal brightness? Justify your answer.
Answer:
When the switch is turned ON, all the three bulbs A, B, and C will glow. They will glow with equal brightness because the electric current flows equally through each bulb. The bulbs are connected properly in the circuit, so
each one gets the same amount of electricity.
Electricity Circuits and Their Extra Questions for Practice
Question 1.
The picture shows an electric cell.
Fill the boxes with the correct symbol (+/-) to show the terminals.
Question 2.
What is the function of a switch in a circuit?
Question 3.
What is the source of electricity in a torch?
Question 4.
An electric bulb is connected to a cell through a switch as shown in figure. When the switch is brought in ON position, the bulb does not glow. What could be the possible reasons for it? Mention any two of them.
Question 5.
Why should we not touch electrical appliances with wet hands?
Question 6.
(a) Name any four components of an electric circuit and write their functions.
(b) What is the role of a switch in a circuit ? What happens when it is OFF?
(c) Why is it important to use wires made of metals like copper in circuits?