Grade 7 : Science (Curiosity) - 3. Electricity (Set 3)

Question 1

A simple circuit consists of a battery and three identical light bulbs connected in series. When one of the bulbs unexpectedly burns out, a student decides to add a new bulb to the circuit.

If the student connects the new bulb in parallel with the *remaining two working bulbs* (which are still in series with each other), how will the brightness of the two original working bulbs change compared to their initial brightness before the first bulb burnt out?

Accepted Answer

C) Their brightness will remain the same.

Answer

A) They will become brighter.

Answer

B) They will become dimmer.

Answer

D) Only one will become brighter, the other dimmer.

Answer

E) They will not light up at all.

Question 2

Imagine you have a complex electrical toy that stops working. You suspect a broken wire inside. You decide to replace a section of the internal wiring.

Which of the following materials would be the *most effective* choice to ensure the toy functions efficiently, considering both electrical conductivity and durability for a flexible wire?

Accepted Answer

A) Copper wire with a PVC coating.

Answer

B) Pure silver wire without any coating.

Answer

C) Aluminum foil wrapped in paper.

Answer

D) A thick strand of rubber.

Answer

E) A thin filament of glass.

Question 3

A student is building a simple circuit with a battery, a switch, and a small motor. They observe that the motor sometimes spins when the switch is open and sometimes doesn't spin even when the switch is closed.

What is the *most likely* reason for this inconsistent behavior, assuming the battery has sufficient power and the motor is functional?

Accepted Answer

B) There is a loose connection somewhere in the circuit.

Answer

A) The battery's voltage is fluctuating significantly.

Answer

C) The motor is designed to spin intermittently.

Answer

D) The switch is wired in parallel with the motor.

Answer

E) The wires are made of an insulating material.

Question 4

A small, battery-powered fan is operating. The battery provides electrical energy to the fan's motor.

Which of the following describes the *primary energy transformation* occurring within the fan's motor?

Accepted Answer

C) Electrical energy into mechanical energy and some heat.

Answer

A) Mechanical energy into electrical energy.

Answer

B) Light energy into heat energy.

Answer

D) Chemical energy into sound energy.

Answer

E) Sound energy into electrical energy.

Question 5

Consider a circuit diagram showing a battery, a switch, and two identical bulbs. The switch is connected in series with the battery. One bulb (Bulb A) is connected in series with the switch, and the second bulb (Bulb B) is connected in parallel with Bulb A.

If the switch is closed, what will be the brightness of Bulb A compared to Bulb B?

Accepted Answer

D) The circuit described is not possible as stated.

Answer

A) Bulb A will be brighter than Bulb B.

Answer

B) Bulb B will be brighter than Bulb A.

Answer

C) Both bulbs will have the same brightness.

Answer

E) Neither bulb will light up.

Question 6

Maya is helping her father with some electrical repairs around the house. She observes that he always turns off the main power switch before starting any work and uses tools with insulated handles.

Why is it crucial for Maya's father to use tools with insulated handles when working with electrical circuits, even after turning off the main power?

Accepted Answer

B) To protect against residual charge or accidental re-energizing of the circuit.

Answer

A) To make the tools last longer by preventing corrosion.

Answer

C) To prevent the tools from slipping out of his hands.

Answer

D) To ensure the tools do not get too hot during use.

Answer

E) To help him see better in dimly lit areas.

Question 7

Two identical wires, Wire X and Wire Y, are made of the same material. Wire X is twice as long as Wire Y, but Wire Y is twice as thick as Wire X.

If these wires are used in separate circuits with identical batteries and bulbs, which wire would result in a brighter bulb, assuming all other factors are constant?

Accepted Answer

A) Wire Y would result in a brighter bulb.

Answer

B) Wire X would result in a brighter bulb.

Answer

C) Both wires would result in bulbs of equal brightness.

Answer

D) Neither wire would allow the bulb to light up.

Answer

E) The brightness depends on the type of bulb used.

Question 8

A group of students is discussing how electricity flows. One student uses the analogy of water flowing through pipes, where voltage is like water pressure and current is like the rate of water flow.

Following this analogy, what would be the equivalent of a narrow pipe or a pipe with many obstacles in an electrical circuit?

Accepted Answer

B) A resistor.

Answer

A) A battery.

Answer

C) A switch.

Answer

D) A voltmeter.

Answer

E) An ammeter.

Question 9

During a science experiment, a student rubs a balloon vigorously against her hair. She then holds the balloon near small pieces of paper.

What phenomenon is the student demonstrating, and what will likely happen to the paper pieces?

Accepted Answer

C) Static electricity; the paper pieces will be attracted to the balloon.

Answer

A) Magnetic induction; the paper pieces will rotate around the balloon.

Answer

B) Thermal conduction; the paper pieces will melt.

Answer

D) Chemical reaction; the paper pieces will change color.

Answer

E) Gravitational pull; the paper pieces will fall faster.

Question 10

A simple electromagnet is made by winding insulated wire around an iron nail and connecting the ends of the wire to a battery. The electromagnet is then used to pick up small paper clips.

If the student wants to increase the strength of the electromagnet without changing the battery, what is the most effective modification they can make?

Accepted Answer

A) Increase the number of turns of wire around the nail.

Answer

B) Replace the iron nail with a wooden stick.

Answer

C) Use a thinner wire with fewer turns.

Answer

D) Connect another battery in parallel with the first.

Answer

E) Decrease the current by adding a resistor.

Question 11

A student is trying to make a small light bulb light up using a battery and two wires. They connect one wire from the positive terminal of the battery to the base of the bulb.

What must the student do next to complete a closed circuit and make the bulb light up?

Accepted Answer

D) Connect the second wire from the negative terminal of the battery to the tip (or side contact) of the bulb.

Answer

A) Connect the second wire from the negative terminal of the battery to the positive terminal of the battery.

Answer

B) Connect the second wire from the positive terminal of the battery to the tip of the bulb.

Answer

C) Connect the second wire from the negative terminal of the battery to the base of the bulb.

Answer

E) Touch the second wire to the glass of the bulb.

Question 12

A portable radio operates using batteries, while a desk lamp is plugged into a wall socket.

Which type of electric current is typically supplied by batteries, and which type by a wall socket?

Accepted Answer

A) Batteries supply Direct Current (DC); wall sockets supply Alternating Current (AC).

Answer

B) Batteries supply Alternating Current (AC); wall sockets supply Direct Current (DC).

Answer

C) Both batteries and wall sockets supply Direct Current (DC).

Answer

D) Both batteries and wall sockets supply Alternating Current (AC).

Answer

E) Batteries supply pulsed current; wall sockets supply steady current.

Question 13

Students are discussing various methods of generating electricity. They consider solar panels, wind turbines, and hydroelectric dams.

What common principle underlies how these diverse sources ultimately generate usable electrical energy?

Accepted Answer

B) They all convert some other form of energy into mechanical energy, which then drives a generator.

Answer

A) They all rely on burning fossil fuels to heat water.

Answer

C) They all use chemical reactions to produce electrons directly.

Answer

D) They all harness the power of static electricity build-up.

Answer

E) They all use nuclear fission to release energy.

Question 14

Consider a circuit with a battery and two identical light bulbs, Bulb A and Bulb B, connected in series. Initially, both bulbs glow with a certain brightness.

If a third identical bulb (Bulb C) is then connected in parallel with Bulb A, how will the brightness of Bulb B change, and how will the overall current from the battery change?

Accepted Answer

A) Bulb B will become brighter, and the overall current will increase.

Answer

B) Bulb B will become dimmer, and the overall current will decrease.

Answer

C) Bulb B's brightness will remain the same, and the overall current will decrease.

Answer

D) Bulb B will become brighter, and the overall current will decrease.

Answer

E) Bulb B will become dimmer, and the overall current will increase.

Question 15

A household electric heater transforms electrical energy into heat energy. A light bulb transforms electrical energy into light and heat energy. A motor transforms electrical energy into mechanical and heat energy.

Which fundamental law of physics is consistently demonstrated by these energy transformations within electrical devices?

Accepted Answer

B) The Law of Conservation of Energy.

Answer

A) Ohm's Law.

Answer

C) Newton's Third Law of Motion.

Answer

D) Archimedes' Principle.

Answer

E) The Law of Universal Gravitation.

Set 3Grade 7 : Science (Curiosity) - Electricity

Grade 7 : Science (Curiosity) - Electricity

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Set 3Grade 7 : Science (Curiosity) - Electricity

Grade 7 : Science (Curiosity) - Electricity

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Set 3Grade 7 : Science (Curiosity) - Electricity

Grade 7 : Science (Curiosity) - Electricity

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Rating & Discussion Locked

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