Kirchhoff's Laws Intermediate Quiz

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Questions and Answers

In the circuit with the variable resistor R, what is the purpose of adjusting R until the current measured by the ammeter is zero?

To balance the potential difference across the test battery and the voltage drop across R. (correct)

To maximize the current flowing through the circuit.

To determine the internal resistance of the test battery.

To minimize the current flowing through the circuit.

Kirchhoff's laws can be used to determine the current in a circuit with multiple loops and branches.

True (A)

What are the two primary laws used in Kirchhoff's laws to analyze circuits?

Kirchhoff's current law (KCL) and Kirchhoff's voltage law (KVL)

In the circuit with the open switch S, the current measured by the ammeter is 0.25 A. This value represents the ______ of the cell.

short-circuit current Signup and view all the answers

Match the following terms with their corresponding descriptions:

Electromotive force (e.m.f.) = The potential difference across the terminals of a battery when no current is flowing. Internal resistance = The resistance offered by the internal components of a battery to the flow of current. Short-circuit current = The maximum current that a battery can deliver when its terminals are connected directly by a wire. Signup and view all the answers

Kirchhoff's first law states that the algebraic sum of currents entering a junction in an electrical circuit is equal to the algebraic sum of currents ______ the junction.

leaving Signup and view all the answers

What is the name of the quantity conserved by Kirchhoff's first law?

Charge (C) Signup and view all the answers

In a circuit with two branches, one with a current of 2.0 A and the other with a current of 1.5 A, what is the total current entering the junction?

3.5 A Signup and view all the answers

Which of the following combinations of cells with an e.m.f. of 1.5 V each will result in a total e.m.f. of 4.5 V?

Three cells connected in series (A) Signup and view all the answers

Kirchhoff's second law states that the sum of the potential drops across all the components in a closed loop is equal to the sum of the e.m.f.s in the loop.

True (A) Signup and view all the answers

Calculate the current I in a circuit with a 10 Ω resistor and a 6.0 V battery using Kirchhoff's second law.

0.6 A Signup and view all the answers

In a parallel circuit, the ______ across each branch is the same.

voltage Signup and view all the answers

Match the following terms with their definitions:

Kirchhoff's first law = The algebraic sum of currents entering a junction is equal to the algebraic sum of currents leaving the junction. Kirchhoff's second law = The sum of the potential drops across all components in a closed loop is equal to the sum of the e.m.f.s in the loop. e.m.f. = The energy supplied per unit charge by a source of electrical energy potential drop = The decrease in electrical potential energy per unit charge as it moves through a component Signup and view all the answers

What are the two main methods for determining the electromotive force (e.m.f.) of a cell?

The two main methods are connecting a high-resistance voltmeter across the cell's terminals and using Kirchhoff's second law. Signup and view all the answers

In the experiment described, increasing the e.m.f. of the supply (Es) will always result in a higher current (I) in the circuit.

False (B) Signup and view all the answers

According to Kirchhoff's second law, the sum of the in a closed loop is equal to the sum of the in that loop.

Signup and view all the answers

In determining the circuit current (I) in Example 2, the equation Σ e.m.f. = Σ p.d. is applied. What does Σ p.d. represent?

The sum of the potential differences across all the resistors in the circuit. (A) Signup and view all the answers

In a series circuit, the value of current is always the same due to conservation of charge.

True (A) Signup and view all the answers

What is the unit of measurement for electromotive force (e.m.f.)?

Volt (V) Signup and view all the answers

Kirchhoff's ______ law states that the algebraic sum of the currents entering a junction is equal to the algebraic sum of the currents leaving the junction.

first Signup and view all the answers

In Example 1, applying Kirchhoff's first law to point Y gives us:

80 = I1 + I2 (D) Signup and view all the answers

In Example 2, the 0.90 V cell is considered 'reversed' because it is connected in the opposite direction to the other cells.

True (A) Signup and view all the answers

What is the purpose of Kirchhoff's laws in the context of electrical circuits?

Kirchhoff's laws provide a fundamental framework for analyzing and solving problems related to current, voltage, and resistance in electrical circuits. Signup and view all the answers

In the first circuit, which direction does the current flow through resistor C?

From left to right (A) Signup and view all the answers

In the first circuit, calculate the total resistance of the two resistors in parallel.

7.0 Ω Signup and view all the answers

Kirchhoff's first law states that the of currents entering a junction equals the of currents leaving the junction.

sum Signup and view all the answers

In the first circuit, the current through resistor D is 0.35 A.

False (B) Signup and view all the answers

In the second circuit, what is the value of the electromotive force (e.m.f.) for the circuit loop containing the 100 Ω resistor?

6.0 V Signup and view all the answers

Match the following descriptions with the corresponding physical concepts:

Kirchhoff's first law = The algebraic sum of the potential differences around any closed loop in a circuit is zero. Kirchhoff's second law = The algebraic sum of the currents entering a junction equals the algebraic sum of the currents leaving the junction. Signup and view all the answers

Kirchhoff's second law is based on the principle of ______ of energy.

conservation Signup and view all the answers

In the second circuit, what is the current I2?

0.14 A (B) Signup and view all the answers

What is the purpose of adjusting the variable resistor R in a circuit until the current measured by the ammeter is zero?

When the current through the ammeter is zero, the potential difference across the variable resistor is equal to the electromotive force (EMF) of the test cell. Signup and view all the answers

In a series circuit, the current is the same throughout the circuit.

True (A) Signup and view all the answers

What is the value of the current I in the circuit with the clockwise loop? (Refer to the circuit diagram in the content)

5.6 × 10⁻² A (D) Signup and view all the answers

How is Kirchhoff's first law used to determine the current I3 in the circuit with two loops?

Kirchhoff's first law is used to determine the current I3 by considering the junction where the currents I1, I2, and I3 meet. The sum of the currents entering the junction (I1 and I2) is equal to the current leaving the junction (I3). Signup and view all the answers

With the switch open in the circuit with the parallel combination, the total resistance of the parallel combination is calculated as ______ Ω.

4.0 Signup and view all the answers

What is the value of the electromotive force (EMF) E in the circuit with the switch closed? (Refer to the circuit diagram in the content)

2.25 V (B) Signup and view all the answers

What is the purpose of the 100 Ω resistor in the circuit?

To provide a known resistance for calculations (D) Signup and view all the answers

According to Kirchhoff's second law, the sum of the electromotive forces (EMFs) in a closed loop is equal to the sum of the potential drops across the components in that loop.

True (A) Signup and view all the answers

What is the relationship between the e.m.f. of the supply (Es) and the e.m.f. of the cell (Ecell) when the current (I) in the circuit is zero?

The e.m.f. of the supply (Es) is equal to the e.m.f. of the cell (Ecell) when the current is zero. Signup and view all the answers

In the provided circuit, the direction of the current is determined by the relative magnitudes of the _____.

e.m.f.s Signup and view all the answers

Match each term with its corresponding definition:

e.m.f. = The potential difference across the terminals of a cell when no current is flowing p.d. = The potential difference across a component when current is flowing I = The rate of flow of charge in a circuit R = The opposition to the flow of current in a circuit Signup and view all the answers

Which of the following is NOT a sensible safety precaution when working with mains-operated supplies?

Check the circuit with a voltmeter before connecting it to the power supply (B) Signup and view all the answers

What is the purpose of plotting a graph of I against Es in this experiment?

The graph helps determine the e.m.f. of the test cell. The point where the line of best fit crosses the horizontal axis (I = 0) corresponds to the e.m.f. of the cell. Signup and view all the answers

The uncertainty in the e.m.f. value obtained from the graph is directly proportional to the slope of the best fit line.

False (B) Signup and view all the answers

Flashcards

Kirchhoff’s First Law

The total current entering a junction equals the total current leaving.

Conserved Quantity

Kirchhoff’s first law conserves electric current.