Equivalent Resistance of a System of Resistor

Q.

Three resistors are connected as shown in the diagram.

Through the resistor 5 ohm, a current of 1 ampere is flowing.
(i) What is the current through the other two resistors?
(ii) What is the p.d. across AB and across AC?
(iii) What is the total resistance?

Q.

In the circuit shown below, calculate the value of x if the equivalent resistance between the points A and B is $4\Omega$.

Q.

Calculate the equivalent resistance between the points A and B in the figure if each resistance is $2.0\Omega$.

Q.

For the circuit shown in the diagram below:

What is the value of:
(i) current through $6\Omega$ resistor?
(ii) potential difference across $12\Omega$ resistor?

Q.

The potential difference between the terminals of an electric heater is 60V when it draws a current of 4A from the source. What current will the heater draw if the potential difference is increased to 120V

Q.

Two resistors $400\Omega$ and $800\Omega$ are connected in series across a $6V$battery. The potential difference measured by a voltmeter of $10k\Omega$ across $400\Omega$ resistors is close to:

1. $2.05V$

2. $2V$

3. $1.95V$

4. $1.8V$

Q.

What happens to the other bulbs in a parallel circuit if one bulb blows off?

Q.

An electric heater can boil a certain amount of water in 10 minutes and another heater can do it in 15 minutes, both working at the same voltage. If the two heaters are connected parallel across the same voltage as before, how much time will they take to boil the same amount of water?

Q.

If two resistors of $25\Omega$ and $15\Omega$ are joined together in series and then placed in parallel with a $40\Omega$ resistor, the effective resistance of the combinations is:
(a) 0.1 $\Omega$ (b) 10 $\Omega$ (c) 20 $\Omega$ (d) 40 $\Omega$

Q.

The V-I Graph for a series combination and for a parallel combination of two resistance is shown in the figure. Which of the two, A or B, represents the parallel combination? Give a reason for your answer.

Q.

In the circuit diagram given below five resistances of $10\Omega ,40\Omega ,30\Omega ,20\Omega ,and60\Omega$
are connected as shown to a 12 V battery.

Calculate :
(a) total resistance in the circuit.
(b) total current flowing in the circuit.

Q.

Five resistors, each of $3\Omega$ are connected as shown in the figure. Calculate the resistance

(a) between the points P and Q, and

(b) between the points X and Y.

Q.

The V-I graph for a series combination and for a parallel combination of two resistors is as shown in the figure below:

Which one of these represent parallel connection.

1. A

2. Cannot be predicted from the graph

3. B

4. Both A and B

Q.

Three resistors each of 4 Ohm are connected in the form of an equilateral triangle. The effective resistance across any two corners is:

1. 8 Ohm

2. 12 Ohm

3. Ohm

4. Ohm

Q. Four cells each of EMF 2V and internal resistance $0.1\Omega$ are connected in series. The combination is connected in series to an ammeter of negligible resistance, a $1.6\Omega$ resistor and an unknown resistor $R_1$. The current in the circuit is 2A. Draw a labelled circuit diagram for the arrangement and calculate the:
(a) value of $R_1$.
(b) potential difference across $R_1$
[5 MARKS]

Q.

The equivalent resistance of the following circuit diagram is 4 Ω. Calculate the value of x.

1. 5 Ω

2. 4 Ω

3. 2 Ω

4. 1 Ω

Q. A wire of resistance R is bent in form of a closed circle, what is the resistance across a diameter of the circle?

Q.

Three resistors each of $2\Omega$ are connected together so that their total resistance is $3\Omega$. Draw a diagram to show this arrangement and check it by calculation.

Q.

Two resistors having resistance $4\Omega$ and $6\Omega$ are connected in parallel. Find their equivalent resistance.

Q.

The circuit diagram given below shows the combination of three resistors $R_1,R_2,and{R}_3$
Find

(i) total resistance of the circuit.
(ii) total current flowing in the circuit.
(iii) the potential difference across $R_1$

Q.

Calculate the effective resistance between the points A and B in the network shown below in the figure.

Q.

What is the resistance between A and B in the figure given below?

Q.

How come the potential difference changes in resistors in series

Q.

Resistors $R_1$, $R_2$ and $R_3$ having values 5 $\Omega$, 10 $\Omega$, and 30 $\Omega$ respectively are connected in parallel across a battery of 12 volts. Calculate

(a) the current through each resistor

(b) the total current in the circuit and

(c) the total circuit resistance

Q.

You are supplied with a number of $100\Omega$ resistors. How could you combine some of these resistors to make a $250\Omega$ resistor?

Q.

What is the virtual value or effective value of a.c. ?

Q.

A wire of resistance $R_1$ is cut into five equal pieces. These five pieces of wire are then connected in parallel.
If the resultant of this combination be $R_2$ then the ratio $\frac{R_1}{R_2}$ is:
(a) $\frac{1}{25}$ (b) $\frac{1}{5}$ (c) 5 (d) 25

Q.

In the network shown in the figure, calculate the equivalent resistance between the points (a) A and B, and (b) A and C.

Q. Why do we need potential difference

Q.

The diagram below shows part of a circuit:

If this arrangement of three resistors was to be replaced by a single resisitor, its resistance should be
$\left(a\right)9\Omega \left(b\right)4\Omega \left(c\right)6\Omega \left(d\right)18\Omega$