9. Flashcards
- Consider the following statements regarding electric circuits:
1 A circuit will function only if it forms a closed loop.
2 An open circuit does not allow the flow of electric current.
3 A switch always creates a closed circuit when turned on.
Which of the statements given above is/are correct?
a) 1 and 2 only
b) 1 and 3 only
c) 2 and 3 only
d) 1, 2, and 3
Answer:
a) 1 and 2 only
Explanation:
A switch can either complete or break a circuit when turned on, depending on its position in the circuit. Thus, statement 3 is incorrect.
- Which of the following correctly describes the flow of current in a circuit connected to an electric cell?
a) Current flows from the positive terminal to the negative terminal outside the cell.
b) Current flows from the negative terminal to the positive terminal inside the cell.
c) Current flows in both directions within the cell simultaneously.
d) Both a) and b) are correct.
Answer:
d) Both a) and b) are correct.
Explanation:
Electric current flows from the positive terminal to the negative terminal outside the cell, while inside the cell, the flow is from the negative terminal to the positive terminal.
Consider the following statements regarding electric cells:
1 An electric cell always produces alternating current (AC).
2 The chemical reactions inside an electric cell produce electrical energy.
3 An electric cell stops functioning when its chemicals are used up.
Which of the statements given above is/are correct?
a) 1 and 2 only
b) 2 and 3 only
c) 1 and 3 only
d) 1, 2, and 3
Answer:
b) 2 and 3 only
Explanation:
An electric cell produces direct current (DC), not alternating current (AC), making statement 1 incorrect.
Consider the following statements regarding electric current in a circuit:
1 The flow of electrons is in the direction opposite to the conventional current.
2 The potential difference between two points in a circuit is the driving force for current flow.
3 Electric current in metals is due to the flow of positively charged particles.
Which of the statements given above is/are correct?
a) 1 and 2 only
b) 2 and 3 only
c) 1 and 3 only
d) 1, 2, and 3
Answer:
a) 1 and 2 only
Explanation:
Electric current in metals is due to the flow of electrons, which are negatively charged particles, making statement 3 incorrect.
In an electric circuit, if the resistance increases, what happens to the current, assuming the voltage remains constant?
a) Current increases.
b) Current decreases.
c) Current remains unchanged.
d) None of the above.
Answer:
b) Current decreases.
Explanation:
According to Ohm’s Law (
I
=
V
R
I=
R
V
), current is inversely proportional to resistance.
Which of the following conditions is necessary for an electric bulb to glow in a circuit?
The circuit must be closed.
The current must be greater than a certain threshold value.
The filament must be intact.
Select the correct answer using the code below:
a) 1 and 2 only
b) 1 and 3 only
c) 2 and 3 only
d) 1, 2, and 3
Answer:
d) 1, 2, and 3
Explanation:
A closed circuit ensures current flow, an intact filament allows the current to produce light, and a minimum current is required to heat the filament sufficiently.
Which of the following materials is NOT commonly used as a filament in electric bulbs?
a) Tungsten
b) Carbon
c) Copper
d) Tantalum
Answer:
c) Copper
Which of the following is a correct application of conductors and insulators in electrical circuits?
Copper wires are used to transmit current due to their high conductivity.
Plastic coatings on wires act as insulators to prevent accidental shocks.
Aluminum is used in electric transmission lines because it is lighter than copper.
Select the correct answer using the code below:
a) 1 and 2 only
b) 2 and 3 only
c) 1 and 3 only
d) 1, 2, and 3
Answer:
d) 1, 2, and 3
Explanation:
All the given statements correctly describe the applications of conductors and insulators.
What will happen to the brightness of a bulb in a circuit if a second identical bulb is added in parallel?
a) The brightness of both bulbs will decrease.
b) The brightness of both bulbs will increase.
c) The brightness of both bulbs will remain the same.
d) The first bulb will glow brighter than the second.
Answer:
c) The brightness of both bulbs will remain the same.
Explanation:
In a parallel connection, the voltage across each bulb remains the same, so their brightness does not change.
Consider a scenario where two identical electric bulbs are connected in a circuit. Which of the following conditions will result in both bulbs glowing equally?
a) The bulbs are connected in parallel, and the voltage is equally distributed.
b) The bulbs are connected in series, and the current is the same through both.
c) The bulbs are connected in parallel, and the current is the same through both.
d) Both a) and b)
Answer:
d) Both a) and b)
Explanation:
In parallel, both bulbs receive equal voltage. In series, both bulbs share the same current. In both cases, they glow equally if their resistance is identical.
- If an electric cell is reversed in a circuit, what will happen to the flow of current?
a) The current will stop flowing.
b) The current will reverse direction.
c) The current will flow through only one terminal.
d) The circuit will be damaged permanently.
Answer:
b) The current will reverse direction.
Explanation:
Reversing the electric cell reverses the potential difference, causing the current to flow in the opposite direction.
- Why are materials like nichrome used in heating elements?
a) They have low electrical resistance.
b) They do not oxidize at high temperatures.
c) They allow high current to flow without heating.
d) They are insulators at room temperature.
Answer:
b) They do not oxidize at high temperatures.
Explanation:
Nichrome has high resistance and does not corrode or oxidize easily, making it ideal for heating elements.
