Olympiad Test: Electricity & Circuits - Class 6 MCQ

The third lamp Z is connected parallel to X, so the current gets divided among X and Z. So both bulbs X and Z light dimmer and the bulb Y lights brighter than earlier because current through it increases.

The direction of current will be PQRS because the current flows from positive terminal of the cell to the negative terminal.

In figure (A), both ends of the bulb are connected to the negative terminal of the cell. So, bulb will not glow while in figure (B) and (C), insulating objects like string and rubber band are used. So, the circuit is incomplete and bulb will not glow. Figure (D) represents the complete circuit with proper connection. Hence, the bulb glows in figure (D).

P is the glass cover, Q is the filament, R is the supporting wires, while S is the positive terminal of the bulb.

The plug cover R and connecting wires cover S should be made of electrical insulators.

Graphite is a conductor of electricity.

• Live wire: The wire that carries current from the power source to the electrical appliance.


• Neutral wire: The wire that carries current back from the electrical appliance to the power source.


• Earth wire: The wire that provides a path to safely conduct any leakage current to the ground, preventing electric shock.


• Correct Answer: The wire which carries away the current to the power house is the Neutral wire.

A switch controls the flow of electricity in a circuit. It completes the circuit when "ON" (allowing current to flow) and breaks the circuit when "OFF" (stopping the current). Its main functions are to turn devices on or off and to ensure safety in electrical systems.

(i) Human body is a good conductor of electricity.
This is correct; the human body is conductive due to its water and electrolyte content.

(ii) The air gap surrounding an electric circuit acts as a conductor.
This is incorrect; air is generally an insulator unless ionized (like in a spark).

(iii) Silver conducts electricity better than any other metal.
This is correct; silver has the highest electrical conductivity of all metals.

(iv) When electricity lights up a bulb, no heat is produced.
This is incorrect; some heat is always produced when electricity flows through a bulb.

Based on this analysis, the correct statements are (i) and (iii), which means the answer is 3 (i) and (iii).

In X, the electrical energy is converted into sound energy. In Y, the electrical energy is converted into light energy. In Z, the electrical energy gets converted into heat energy. So, (C) is the correct option.

The rubber gloves are bad conductors of electricity. Hence, they prevent electric current to enter in our body and protect us from electric shocks.

Replacing one cell with a piece of wire reduces the current in the circuit. Hence, the bulbs glow dimmer.

Fuse is a device used for short circuiting the circuit when overloading of current happens which helps to protect the electrical appliances.

Key is a metallic object. When it is placed in between probes then current can easily flow in the circuit.

Brightness of bulb can be increased by increasing the current through the bulb. This can be achieved by connecting a similar battery in the circuit.

When the circuit is closed, an electric current starts flowing in the circuit from the positive terminal of battery. The current which passes through bulb P gets divided and flows in bulbs Q and R. As the brightness depends upon the current flowing through the bulb, so P will be bright but Q and R will be dim.

Since switch S₂ is open and S₁ is closed, the current will pass through Y but for bulb X, the circuit is incomplete. There is no complete path for current to flow for bulb X. Hence, only bulb Y will glow.

Current will flow positive to negative terminal, so all bulbs will glow simultaneously.

Bulb Q is fused because its filament is broken and as it is fused the circuit is broken. So none of the bulb will glow.

The torch is not glowing because either its bulb is fused or cells are connected wrongly or metal spring of torch does not make proper contact with the cell.