Internal resistance of cells and Kirchhoff’s laws - One Line Questions
1.
If a cell has an EMF of 1.5 V and an internal resistance of 0.5 ohms, what is the current when connected to an external resistance of 2.5 ohms? —
0.6 A
2.
If a cell has an EMF of 1.5 V and internal resistance of 0.5 ohms, what is the current when it is short-circuited? —
3.0 A
3.
If a cell has an EMF of 2V and internal resistance of 1 ohm, and it is connected to an external resistance of 3 ohms, what is the terminal voltage? —
1.5 V
4.
If a cell is connected to an external resistance equal to its internal resistance, the efficiency of power transfer is: —
50%
5.
What is the SI unit of electromotive force (EMF)? —
Volt
6.
In a complex electrical circuit, Kirchhoff's laws are essential for: —
Analyzing and solving for currents and voltages in each part
7.
Kirchhoff's Second Law is a direct consequence of the conservation of: —
Energy
8.
If a cell's internal resistance is very high compared to the external resistance, the terminal voltage will be: —
Much less than the EMF
9.
What does Kirchhoff's Second Law represent in terms of energy? —
Conservation of energy
10.
What happens to the internal resistance of a cell when its electrolyte ages or decomposes? —
Increases
11.
Consider a cell with EMF E and internal resistance r. If it is connected to an external resistance R, the potential difference across R is given by: —
E - Ir
12.
What is the potential drop across the internal resistance of a cell when it is delivering current I? —
Ir
13.
If a cell has an EMF of E and internal resistance r, and it is connected to an external resistance R, what is the current flowing through the circuit? —
E / (R + r)
14.
What is the maximum possible current that can be drawn from a cell with EMF E and internal resistance r? —
E / r
15.
In a series combination of two cells with EMFs E1, E2 and internal resistances r1, r2, what is the equivalent EMF? —
E1 + E2
16.
What is the effective EMF of two cells connected in series, with EMFs E1 and E2, and E1 > E2? —
E1 + E2
17.
In a parallel combination of two cells with EMFs E1, E2 and internal resistances r1, r2, for stable operation, it is generally required that: —
E1 = E2 and r1 = r2
18.
Kirchhoff's First Law is based on the conservation of which quantity? —
Charge
19.
What is the potential difference across the terminals of a cell when it is delivering current? —
Less than its EMF
20.
What is the term for the resistance offered by the electrolyte and electrodes within a cell? —
Internal resistance
21.
What is the condition for maximum power transfer from a source to an external load? —
External resistance equals internal resistance
22.
When a cell is discharged, the current flows: —
From negative to positive terminal internally
23.
When a cell is charged by an external source, the current flows: —
Opposite to the direction of discharge
24.
What is the power dissipated internally by a cell with EMF E, internal resistance r, delivering current I? —
I^2 * r
25.
A galvanometer is a device used to detect and measure small electric currents. How is it typically connected in a circuit to measure current? —
In series
26.
A voltmeter is used to measure potential difference. How is it connected in a circuit? —
In parallel
27.
A cell of EMF E and internal resistance r is connected to an external resistor R. If R is increased, what happens to the current? —
Decreases
28.
What is the effect of increasing the area of electrodes in a cell on its internal resistance? —
Decreases the internal resistance
29.
What is the condition for a cell to be ideal (no internal resistance)? —
Internal resistance = 0
30.
Which of the following statements about internal resistance is correct? —
It depends on the state of charge of the cell.
31.
The potential difference across the terminals of a cell when it is being charged is: —
Greater than its EMF
32.
Kirchhoff's First Law is also known as the: —
Junction Rule
33.
Which of the following factors DOES NOT affect the internal resistance of a cell? —
External resistance connected
34.
Which law states that the algebraic sum of EMFs and potential drops in any closed circuit is zero? —
Kirchhoff's Second Law (Voltage Law)
35.
Which law is particularly useful for analyzing electrical networks with multiple interconnected components? —
Kirchhoff's Laws
36.
If a circuit diagram has multiple loops and junctions, which method is most suitable for analysis? —
Kirchhoff's Laws
37.
When applying Kirchhoff's Second Law, if we traverse a loop in the direction of the current through a resistor, the potential change is: —
Negative
38.
In Kirchhoff's Second Law, if we traverse a loop in the opposite direction of the current through a resistor, the potential change is: —
Positive
39.
When applying Kirchhoff's Second Law, if we traverse a loop in the direction of an EMF source (from negative to positive terminal), the EMF is taken as: —
Positive
40.
When applying Kirchhoff's Second Law, if we traverse a loop in the opposite direction of an EMF source (from positive to negative terminal), the EMF is taken as: —
Negative
41.
What is the total resistance in a circuit where a cell of EMF E and internal resistance r is connected to an external resistance R? —
R + r
42.
In a parallel combination of two cells with identical EMFs E and internal resistances r1, r2, what is the equivalent internal resistance? —
(r1 * r2) / (r1 + r2)
43.
According to Kirchhoff's First Law, at any junction in an electrical network, the sum of currents flowing towards the junction is equal to: —
The sum of currents flowing away from the junction
44.
What is the primary function of the internal resistance of a cell? —
To limit the current flowing through the cell
45.
When a cell is being charged, the terminal voltage is related to its EMF and internal resistance by which formula? —
V = E + Ir
46.
What is the unit of internal resistance? —
Ohm
47.
If a cell is short-circuited, what is the current flowing through it? —
E / r (internal resistance)
48.
What is the terminal voltage of a cell when it is not connected to any external circuit? —
Equal to its EMF
49.
If the external resistance is increased to infinity (open circuit), what is the terminal voltage of the cell? —
E