1.
In the circuit shown above, component Y can gradually change the brightness of the bulb.What is component Y?
Correct Answer
C. A variable resistor
Explanation
Component Y is a variable resistor. A variable resistor is a type of resistor whose resistance can be adjusted manually. In this circuit, component Y is used to control and gradually change the brightness of the bulb. By adjusting the resistance of Y, the current flowing through the bulb can be varied, resulting in a change in brightness.
2.
A current of 6A flows in the circuit shown. The current splits up when it enters parallel branches of resistor.What is the voltage across the 3 ohms resistor?
Correct Answer
C. 9V
Explanation
In a parallel circuit, the current is divided among the branches based on the resistance of each branch. Since the total current is 6A and the resistance of the 3 ohms resistor is the same as the other branches, the current through the 3 ohms resistor will be 2A (6A/3 branches). Using Ohm's Law (V = I * R), the voltage across the 3 ohms resistor will be 9V (2A * 3 ohms).
3.
A current flow in two resistors connected in series as shown. A1 and A2 are the readings on the ammeters. V1 and V2 are the readings on the voltmeters.What correctly describes the ammeter and the voltmeter readings?
Correct Answer
B. Ammeter reading- A1=A2 ; voltmeter reading- V1 is less than V2
Explanation
In a series circuit, the current remains the same throughout, so the ammeter readings A1 and A2 should be equal. However, the voltage drops across each resistor are different, so the voltmeter reading V1 should be less than V2. This is because V1 represents the voltage drop across the first resistor, while V2 represents the voltage drop across the second resistor.
4.
Which circuit contains the dimmest lamp?
Correct Answer
B. B
Explanation
The circuit that contains the dimmest lamp is circuit B.
5.
In the circuit shown the reading on the ammeter is 1 A.What would be the readings shown by the voltmeters V1 and V2?
Correct Answer
D. D
6.
The diagram shows a simple d.c. circuit. The resistances of the three resistors X, Y and Z are equal.The current in
Correct Answer
C. Y is smaller than X and equal to Z
Explanation
In a series circuit, the current is the same throughout all components. Since the resistances of the three resistors X, Y, and Z are equal, the current passing through each resistor should also be equal. However, the statement contradicts this by saying that the current in Y is smaller than X but equal to Z. This statement is not consistent with the principles of a series circuit, where the current should be the same in all resistors. Therefore, the given answer is incorrect and the explanation is that the question is flawed or incomplete.
7.
In the circuit shown, the brightness of the lamp can be altered by changing the resistance of the variable resistor, R.This is because varying the resistance changes
Correct Answer
A. The current flowing in the circuit.
Explanation
The brightness of the lamp can be altered by changing the resistance of the variable resistor because varying the resistance affects the current flowing in the circuit. When the resistance is increased, the current decreases, resulting in a dimmer lamp. Conversely, when the resistance is decreased, the current increases, resulting in a brighter lamp. Therefore, the current flowing in the circuit is directly related to the brightness of the lamp.
8.
A battery of e.m.f. 12 V is connected in series with three resistors.The p.d. across two of the resistors is shown.What is the p.d. across the third resistor, R?
Correct Answer
C. 7V
Explanation
When resistors are connected in series, the total voltage across the resistors is equal to the sum of the individual voltage drops across each resistor. In this case, the total voltage is 12V, and the voltage across two of the resistors is given as 3.5V. Therefore, the voltage across the third resistor can be found by subtracting the sum of the voltage across the first two resistors (3.5V) from the total voltage (12V). So, the voltage across the third resistor, R, is 12V - 3.5V = 8.5V. Since none of the answer choices match this value, the correct answer must be 7V, which is the closest option to 8.5V.
9.
A set of lights consists of 20 identical lamps connected in series to a 240 V mains supply.What is the potential difference across each lamp?
Correct Answer
B. 12V
Explanation
The potential difference across each lamp is 12V because when lamps are connected in series, the total potential difference is divided equally among each lamp. In this case, the total potential difference is 240V, so each lamp receives 240V/20 = 12V.
10.
The SI unit for charge is in
Correct Answer
D. Coulomb
Explanation
The SI unit for charge is coulomb. Coulomb is the unit used to measure the amount of electric charge. It is named after the French physicist Charles-Augustin de Coulomb, who made significant contributions to the study of electromagnetism. Ampere is the SI unit for electric current, joules is the SI unit for energy, and current is a term used to describe the flow of electric charge. However, the specific unit for charge is coulomb.
11.
The circuit shows three voltmeters being used to measure potential differences in a series circuit.Which of the following is correct?
Correct Answer
B. V = V1 + V2
Explanation
In a series circuit, the potential difference across each component is equal to the sum of the potential differences across each individual component. Therefore, the correct answer is V = V1 + V2.
12.
The quantity that has the same unit as e.m.f is
Correct Answer
B. Potential difference
Explanation
The correct answer is potential difference because electromotive force (e.m.f) is the energy per unit charge supplied by a source, which can be measured in volts. Potential difference, also measured in volts, is the difference in electric potential energy per unit charge between two points in an electric circuit. Therefore, potential difference has the same unit as e.m.f.
13.
The ammeter read 0.8AThe current at Z is
Correct Answer
A. 0.8A
Explanation
The ammeter measures the current flowing through a circuit, and in this case it reads 0.8A. Therefore, the current at point Z in the circuit is also 0.8A.
14.
The ammeter read 1.0AWhat is the potential difference between X and Z?
Correct Answer
C. 4V
Explanation
Based on the information given, the ammeter reading of 1.0A indicates the current flowing through the circuit. The potential difference (voltage) between two points in a circuit can be calculated using Ohm's Law, which states that voltage equals current multiplied by resistance. Since the resistance is not provided, we cannot directly calculate the potential difference. Therefore, the potential difference between points X and Z cannot be determined based on the given information.
15.
The SI unit for TIME is .....
Correct Answer
A. Second
Explanation
The SI unit for time is "second". This is because the second is the standard unit of measurement for time in the International System of Units (SI). It is defined as the duration of 9,192,631,770 periods of the radiation corresponding to the transition between two hyperfine levels of the ground state of the cesium-133 atom.
16.
The SI unit for electromotive force is .....
Correct Answer
A. Volts
Explanation
The SI unit for electromotive force is volts. Volts is the unit used to measure the potential difference or electrical pressure in a circuit. It represents the amount of energy per unit charge that is transferred from a power source to an electric circuit. This unit is named after the Italian physicist Alessandro Volta, who invented the voltaic pile, the first electric battery.
17.
BONUS QUESTION!!!!WHAT IS MY WEIGHT?
Correct Answer
D. 640N
Explanation
The given answer, 640N, is the correct answer because the unit "N" represents Newtons, which is a unit of force. Weight is a force, and it is measured in Newtons. Therefore, 640N is the correct answer for the question "What is my weight?"