Electrical Energy
25 Grade 7 Integrated Science questions on Electrical Energy, with worked marking schemes. 25 questions are available on this topic in full.
Question 1
1 markA device that stores chemical energy and changes it into electrical energy to run a circuit is a:
A. Switch
B. Cell (battery)
C. Resistor wire
D. Bulb
(1 mark)
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4 marksA simple electric circuit is made up of a cell, a switch, connecting wires and a bulb.
(a) State the function of the cell in the circuit. (1 mark)
(b) State the function of the switch. (1 mark)
(c) Explain what happens to the bulb when one of the connecting wires is disconnected, and why. (2 marks)
(4 marks)
Marking scheme
(a) The cell provides (supplies) the electrical energy / it is the source of electric current in the circuit. (1 mark) (b) The switch is used to open or close the circuit, that is to turn the current (and the bulb) on or off. (1 mark) (c) The bulb goes off (does not light). This is because disconnecting a wire breaks the circuit, so it is no longer a complete (closed) circuit and current cannot flow through the bulb. (2 marks)
Question 3
1 markIn an electric bulb, electrical energy is mainly transformed into:
A. Sound energy only
B. Chemical energy only
C. Mechanical energy only
D. Light energy and heat energy
(1 mark)
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1 markA material that allows electricity to pass through it is called a
A. capacitor
B. insulator
C. resistor
D. conductor
(1 mark)
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1 markLearners connected materials to make a simple electric circuit. The bulb lit when they used a nail but did not light with a plastic ruler. This is because
A. both are conductors
B. a nail is an insulator and plastic is a conductor
C. a nail is a conductor and plastic is an insulator
D. both are insulators
(1 mark)
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1 markWhich of the following materials is a good electrical conductor?
A. Plastic rod
B. Copper wire
C. Rubber band
D. Glass rod
(1 mark)
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4 marks(a) Name three components needed to make a simple electric circuit that lights a bulb. (3 marks)
(b) State one way of saving electrical energy at home. (1 mark)
(4 marks)
Marking scheme
(a) Any three of: a cell/battery (source of energy); connecting wires; a bulb; a switch. (1 mark each) (b) Any one of: switch off lights/appliances when not in use; use energy-saving bulbs; unplug appliances not in use; use natural daylight instead of electric light. (1 mark)
Question 8
3 marksState three safety measures to observe when handling electrical appliances.
(3 marks)
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1 markAn electrical insulator is a material that
A. stores electricity
B. produces electricity
C. does not allow electricity to pass through it
D. allows electricity to flow easily
(1 mark)
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3 marksElectricity must be used safely at home and in school. State three safety precautions that should be observed when using electricity.
(3 marks)
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1 markOperating electrical appliances with wet hands is dangerous because
A. wet hands are stronger
B. water is an insulator
C. water makes electricity weaker
D. water is a conductor of electricity
(1 mark)
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1 markA learner connects two bulbs in series with one cell. When one bulb is removed from its holder, the other bulb goes off. This is because in a series circuit:
A. The current increases when a bulb is removed
B. Each bulb has its own separate path
C. Bulbs in series never light at all
D. There is only one path for the current, so breaking it stops the flow
(1 mark)
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1 markWhich of the following is a renewable source of electrical energy?
A. Diesel
B. Coal
C. Solar energy
D. Natural gas
(1 mark)
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3 marksClassify the following sources of electricity into renewable and non-renewable:
Solar, Coal, Wind, Natural gas, Geothermal, Diesel
(3 marks)
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4 marksA learner sets up a simple electric circuit to light a bulb.
(a) Name three components needed to make the bulb light.
(b) Explain why the bulb will not light if one of the connecting wires is disconnected.
(4 marks)
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1 markAn electric circuit must have a complete path for current to
A. reverse
B. stop
C. flow
D. disappear
(1 mark)
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1 markWhich of the following is a renewable source used to generate electrical energy in Kenya?
A. Diesel fuel
B. Coal
C. Kerosene
D. Wind at the Turkana wind farm
(1 mark)
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5 marksMaterials can be classified according to how they allow electricity to pass.
(a) Define a conductor and an insulator.
(b) Give one example of each and state one everyday use of an insulator.
(5 marks)
Marking scheme
(a) Conductor: a material that allows electric current to flow through it (1 mark). Insulator: a material that does not allow electric current to flow through it (1 mark). (b) Conductor example: copper/aluminium/any metal (1 mark). Insulator example: plastic/rubber/wood/glass (1 mark). Use of insulator: covering electrical wires or cables (or handles of tools) to prevent electric shock (1 mark).
Question 19
4 marks(a) Name two sources of electrical energy used in homes. (2 marks)
(b) State one way of conserving (saving) electrical energy in the home. (1 mark)
(c) Give one safety precaution to observe when using electricity. (1 mark)
(4 marks)
Marking scheme
(a) Any two of: the mains supply from the national grid (hydroelectric/solar/wind/geothermal power station); dry cells/batteries; solar panels; generators. (2 marks) (b) Any one: switching off lights/appliances when not in use; using energy-saving bulbs; unplugging appliances on standby. (1 mark) (c) Any one: do not touch electrical sockets or switches with wet hands; do not overload sockets; do not use damaged/bare wires; switch off the mains before repairs. (1 mark)
Question 20
1 markIn a simple electric circuit, which component is used to open and close the circuit so that current flows only when needed?
A. Battery
B. Switch
C. Bulb
D. Connecting wire
(1 mark)
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4 marks(a) State two sources of electrical energy used in the home. (2 marks)
(b) State two ways of saving (conserving) electrical energy at home. (2 marks)
(4 marks)
Marking scheme
(a) Any two of: the mains supply (from a hydroelectric/solar/wind power station via the national grid); dry cells/batteries; solar panels (photovoltaic cells); a generator. (2 marks) (b) Any two of: switching off lights and appliances when not in use; using energy-saving bulbs (LED/fluorescent); using natural daylight during the day; servicing and maintaining appliances so they work efficiently; not leaving electrical devices on standby. (2 marks)
Question 22
1 markA learner builds a torch. Which of the following materials should be used for the connecting wires to allow current to flow?
A. Dry wood
B. Plastic
C. Copper
D. Rubber
(1 mark)
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1 markWhich of the following is a source of electrical energy?
A. Dry cell (battery)
B. Charcoal
C. Firewood
D. Candle
(1 mark)
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4 marksTwo identical bulbs are connected to the same cell, one arrangement in series and the other in parallel.
(a) State one difference in how the bulbs light in the two arrangements.
(b) Give one advantage of connecting bulbs in parallel in a house.
(4 marks)
Marking scheme
(a) In series the bulbs share the voltage so they are dimmer, and if one bulb fails all go off; in parallel each bulb gets the full voltage so they are brighter and light independently (2 marks). (b) If one bulb or appliance fails or is switched off, the others continue to work (2 marks).
Question 25
1 markWhy is it dangerous to touch electrical switches or appliances with wet hands?
A. Water turns electricity into heat harmlessly
B. Water makes the current flow more slowly and safely
C. Wet hands stop electricity completely
D. Water conducts electricity and can cause an electric shock
(1 mark)
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