Resistors in parallel

Q.

Write the SI unit of Resistivity.

Q.

A wire of $10\mathrm{\Omega }$ resistance stretched to thrice its original length. What will be its

1. New resistivity
2. New resistance

Q.

If a wire of resistance $\mathrm{R}=10\mathrm{ohm}$ is stretched to double of its length, then new resistance will be ______.

Q. Question 18 (c)
Explain:
(c) Why is the series arrangement not used for domestic circuits?

Q.

Why is resistance different in Series and Parallel?

Q.

In the given circuit diagram, a wire is joining points $B\&C$. Find the current in this wire

1. $0.4A$

2. $2A$

3. $0$

4. $4A$

Q. A wire of 10 ohms is bent to form a closed circle.what is the resistance across a diameter of the circle?

Q.

What is the role of neutral wire

Q.

Does the resistance of a copper wire increase or decrease when both the length and diameter of the wire is doubled? Explain your reasoning.

Q.

A wire of resistance 4ohms is bent to form a circle .What is the resistance between two diametrically opposite ends ?

Q.

What is the formula for parallel resistance?

Q.

The decrease of resistance in parallel combination is due to:

1. the decrease in effective area of the cross-section

2. the increase in effective area of the cross-section

3. The decrease in effective length .

4. None of the above

Q.

Five resistors of different resistances are connected together as shown in the figure. A 12 V battery is connected to the arrangement. The total current flowing in the circuit is :

1. 0.67 A

2. 1.00 A

3. 12.00 A

4. 0.33 A

Q.

With reference to the diagram alongside, Calculate:

(a) Equivalent resistance between P and Q.

Q. What is equivalent resistance? Derive the expression for effective resistance of two resistors connected in parallel.

Q.

An electric heater that is connected to a $220V$ supply line has two resistance coils. A and B of $24\Omega$ resistance each. these coils can be used separately (one at a time), in series, or in parallel. Calculate the current drawn when (a) Only one coil A is used and (b) coils A and B are used in series.

Q. What is the effective resistance between points A and B?

1. $\frac{R}{3}$
2. $\frac{4R}{3}$
3. $\frac{2R}{3}$
4. $\frac{R}{2}$

Q.

For the circuit shown in the following diagram, What is the value of

1. current through 6$\Omega$ resistor?

2. potential difference across 12$\Omega$ ? [3 MARKS]

Q.

Question 28 (i)
$B_1,B_2$ and $B_3$ are three identical bulbs connected as shown in figure. When all the three bulbs glow, a current of 3A is recorded by the ammeter A.
(i) What happens to the glow of the other two bulbs when the bulb $B_1$ gets fused?

Q. Show by a diagram how resistors $R_1,R_{2}and{R}_3$ are joined in parallel. Obtain an expression for the total resistance of the combination.
[5 MARKS]

Q.

A hot plate of an electric oven connected to a 220 V line has two resistance coils A and B, each of 24W resistance, which may be used separately in series or in parallel. What are the currents in the three cases?

Q. A resistor of 6 kilo ohm with tolerance 10% and another of 4 kilo ohm with tolerance 10% are connected in series.The tolerance of the combination in parallel is

Q. 2 Resistance in parallel gives 2 ohms and im series gives 9 ohm? what is power of resistances

Q.

If current flow in each branch is different in each branch of electric circuit it is said to be a ______ circuit .

Q. Two resistors of resistances $10\Omega$ and $20\Omega$ are connected in parallel. A battery supplies $6A$ of current to the combination. Calculate the current in each resistor.

Q. What is the effective resistance between points P and Q?

1. 5 $\Omega$
2. 10 $\Omega$
3. 15 $\Omega$
4. 20 $\Omega$

Q. A wire has resistance of $12\Omega$. It is cut into two parts and both halve are connected in parallel. The new resistance is

1. $3\Omega$
2. $1.5\Omega$
3. $6\Omega$
4. $12\Omega$

Q. A wire of resistance R and length L is pulled and stretched to a length 2L. What is its new resistance?

1. 2R
2. 4R
3. $\frac{R}{2}$
4. R

Q. In an electrical cable, there is a single copper wire of radius $6mm$. Its resistance is $10\Omega$. The single wire in the cable is replaced by five different insulated copper wires with the radius of $2mm$ for each wire. The new resistance of the cable is:

1. $50\Omega$
2. $18\Omega$
3. $12\Omega$
4. $90\Omega$

Q.

What is resistance and resistivity? Why is the series arrangement not used for domestic circuits? Two resistors $R_1$ and $R_2$ are joined in series. Find the equivalent resistance. [5 MARKS]