Chapter 14- Electric Current and Its Effects–Class 7 science- Question and Answer -(Solved MCQs)

Chapter 14- Electric Current and Its Effects -Multiple Choice Questions (Solved Worksheet)

Question1- What is the purpose of a circuit diagram?

A) To increase the flow of electricity

B) To visually represent the connections in an electric circuit

C) To physically build electric circuits

D) To repair electronic components

Answer- B) To visually represent the connections in an electric circuit

Explanation- A circuit diagram is used to simplify and visually represent how different components in an electric circuit are connected, using symbols.

Question 2- What does it indicate in a circuit diagram when a switch is shown as closed?

A) The circuit is open

B) The bulb is fused

C) The electric circuit is complete

D) The battery is dead

Answer- C) The electric circuit is complete

Explanation- In a circuit diagram, a closed switch (in the ON position) means that the electric circuit is complete, allowing current to flow.

Question 3 – Which scenario can cause a bulb not to light up even if the switch is ON?

A) The bulb is too bright

B) The bulb is fused or its filament is broken

C) The switch is made of plastic

D) The wires are too long

Answer- B) The bulb is fused or its filament is broken

Explanation- If the bulb’s filament is broken, it interrupts the flow of electricity, much like a broken bridge would stop traffic, preventing the bulb from lighting up.

Question 4 – Why are standardised symbols important in electronic components?

A) They make the circuit look more complex

B) They help in physically constructing circuits

C) They provide a universal language for understanding and designing electrical circuits

D) They are used to reduce electricity consumption

Answer- C) They provide a universal language for understanding and designing electrical circuits

Explanation– Standardised symbols in circuit diagrams allow for a clear and concise representation of circuits, facilitating easy understanding and design worldwide.

Question 5 – What is the function of an electric fuse?

A) To increase the flow of electricity

B) To reduce the heating effect in wires

C) To break the circuit if too much current flows through it

D) To connect multiple electrical appliances

Answer- C) To break the circuit if too much current flows through it

Explanation- Electric fuses are safety devices that melt and break the circuit if the current exceeds a safe level, preventing hazards.

Question 6 – What happens when current flows through a straight wire?

A) It becomes less resistant to current.

B) It produces a magnetic effect around the wire.

C) It automatically cools down.

D) It reduces the current flow.

Answer- B) It produces a magnetic effect around the wire.

Explanation- A current-carrying straight wire exhibits a magnetic effect, a fundamental aspect of electromagnetism.

Question-7 How is the voltage affected when cells are connected in series?

A) It decreases.

B) It remains the same.

C) It increases.

D) It becomes zero.

Answer- C) It increases.

Explanation- Connecting cells in series results in the addition of voltages, thus increasing the total voltage output.

Question 8 – Which of the following is a correct representation of a battery in an electric circuit?

A) Multiple cells connected in series.

B) A single cell with high voltage.

C) Multiple cells connected with positive to positive terminals.

D) A wire without any cells.

Answer- A) Multiple cells connected in series.

Explanation- A battery is essentially multiple electric cells connected, usually in series, to provide a higher voltage than a single cell.

Question 9- What is the primary function of the filament inside an electric bulb?

A) To reflect light

B) To conduct electricity

C) To absorb heat

D) To glow and produce light

Answer- D) To glow and produce light

Explanation- The filament in an electric bulb glows when electric current passes through it, producing light due to the heating effect of the current.

Question 10- What distinguishes Compact Fluorescent Lamps (CFLs) from regular incandescent bulbs?

A) CFLs have a longer filament

B) CFLs use a gas that produces ultraviolet light

C) CFLs are only used for decorative purposes

D) CFLs consume more energy

Answer- B) CFLs use a gas that produces ultraviolet light

Explanation- CFLs do not have a filament; instead, they contain a gas that emits ultraviolet light when electrified, which then produces visible light.

Question 11- How does a fuse prevent electrical hazards?

A) By storing excess electricity

B) By converting electricity into heat

C) By melting and breaking the circuit when excess current flows

D) By increasing the voltage

Answer- C) By melting and breaking the circuit when excess current flows

Explanation- Fuses are safety devices that melt and break the circuit when too much current flows through them, thus preventing hazards like fires or damage to the electrical system.

Question 12 – What triggers the continuous ringing of an electric bell?

A) The constant flow of electricity

B) The uninterrupted magnetization of the electromagnet

C) The repeated making and breaking of the circuit

D) The permanent movement of the armature

Answer- C) The repeated making and breaking of the circuit

Explanation- In an electric bell, the continuous ringing sound is produced by the rapid vibration of the armature caused by the repeated making and breaking of the electric circuit.

Multiple-Choice Questions

Question 13 – What is the main advantage of electromagnets over permanent magnets?

A) They are cheaper to produce

B) They can be turned on or off

C) They are smaller in size

D) They are always stronger

Answer- B) They can be turned on or off

Explanation- Electromagnets have the advantage of control over magnetism, as they can be easily turned on or off by controlling the electric current, unlike permanent magnets.

Question 14- What is the primary function of a Miniature Circuit Breaker (MCB)?

A) To decrease the flow of current

B) To automatically turn off when current exceeds a safe limit

C) To increase the voltage

D) To act as a resistor

Answer- B) To automatically turn off when current exceeds a safe limit

Explanation- MCBs operate on the magnetic effect of current and automatically shut off the circuit when the current flow exceeds safe limits.

Question 15 – What causes overloading in household wiring?

A) Connecting too few appliances to a single socket

B) Using appliances with low power consumption

C) Connecting too many appliances to a single socket

D) The presence of a fuse in the circuit