Electric Bulbs

Q. Five bulbs with power rating $B_1=B_4=60W-200V,B_2=B_3=100W-200V$ and $B_5=40W-200V$ now, 200 V are connected as shown in figure. Then
1. $B_5$ will glow the most
2. $B_1$ will glow more than $B_4$
3. $B_2$ and $B_3$ will glow the most

1. None
2. 1, 2, and 3 are correct
3. 1 and 2 are correct
4. Only 1 is correct

Q. The balancing lengths of potentiometer wire are $l_1$ and $l_2$ when two cells of emf $E_1$ and $E_2$ are connected in the secondary circuit in series. first to support each other and next to oppose each other. Then the ratio of $\frac{E_1}{E_2}$ is equal to [if $E_1>E_2$]

1. $\frac{l_1-l_2}{l_1+l_2}$
2. $\frac{l_1+l_2}{l_1-l_2}$
3. $\frac{l_1}{l_2}$
4. $\frac{l_2}{l_1}$

Q. A potentiometer circuit has been set up for finding the internal resistance of a given cell. The main battery, used across the potentiometer wire, has an emf of $2\text{V}$ and a negligible internal resistance. The potentiometer wire itself is $4\text{m}$ long. When the resistance $R$ is connected across the given cell has value of $\left(i\right)$ infinity, $\left(ii\right)9.5\Omega$ the balancing length on the potentiometer wire are found to be $3\text{m}$ and $2.85\text{m}$ respectively. The value of internal resistance of the cell is

1. $0.25\Omega$
2. $0.95\Omega$
3. $0.5\Omega$
4. $0.75\Omega$

Q. A torch bulb rated as 4.5 W, 1.5 V is connected as shown in the figure. The emf of the cell needed to make the bulb glow at full intensity is

1. 4.5 V
2. 1.5 V
3. 2.67 V
4. 13.5 V

Q. The circuit below is made up using identical light bulbs. The light bulb of maximum brightness among the following will be

1. $A$
2. $C$
3. $D$
4. $E$

Q. In the given potentiometer circuit arrangement, the balancing length $\text{AC}$ is measured to be $250\text{cm}$. When the galvanometer connection is shifted from point $\left(1\right)$ to point $\left(2\right)$ in the given diagram, the balancing length becomes $400\text{cm}$. The ratio of the emf of two cells, $\frac{E_1}{E_2}$ is:

1. $\frac{5}{3}$
2. $\frac{8}{5}$
3. $\frac{3}{2}$
4. $\frac{4}{3}$

Q. Which of the following acts as a circuit protection device?

1. Conductor
2. Inductor
3. Switch
4. Fuse

Q. In the given potentiometer circuit length of the wire $\text{AB}$ is $3\text{m}$ and resistance is $R=4.5\Omega$. The length $\text{AC}$ for no deflection in galvanometer is

1. $1.5\text{m}$
2. $2\text{m}$
3. $1.8\text{m}$
4. $2.5\text{m}$

Q. An ideal battery of $4\text{V}$ and resistance $R$ are connected in series in the primary circuit of a potentionmeter of length $1\text{m}$ and resistance $5\Omega .$ The value of $R,$ to give a potential difference of $5\text{mV}$ across $10\text{m}$ of potentiometer wire is:

1. $395\Omega .$
2. $495\Omega .$
3. $480\Omega .$
4. $490\Omega .$

Q. Three bulbs $B_1,B_2$ and $B_3$ are connected to the mains as shown in the figure. How will the brightness of bulb $B_1$ be affected if $B_2$ or $B_3$ are disconnected from the circuit?

1. Bulb $B_1$ becomes brighter
2. Bulb $B_1$ becomes dimmer
3. No change occurs in the brightness
4. Bulb $B_1$ becomes brighter if bulb $B_2$ is disconnected and dimmer if bulb $B_3$ is disconnected

Q. In the circuit diagram, all the bulbs are identical. Bulb will be the brightest.

1. A
2. B
3. C
4. D

Q. A potentiometer wire gives a null point at $3\text{m}$ for a wire of length $3.5\text{m}$. The primary circuit contains only a battery of emf $10\text{V}$. The emf of secondary cell is $8\text{V}$. What is the internal resistance of the battery in the primary circuit (in ohms) if the resistance of the potentiometer wire is $14\Omega$?

Q. In the circuit shown, a four - wire potentiometer is made of a $400\text{cm}$ long wire, which extends between $\text{A}$ and $\text{B}$. The resistance per unit length of the potentiometer wire is $x=0.01\Omega /\text{cm}$. If an ideal voltmeter is connected as shown with jockey $J$ at $50\text{cm}$ from end $\text{A}$, the expected reading of the voltmeter will be

1. $0.20\text{V}$
2. $0.75\text{V}$
3. $0.25\text{V}$
4. $0.50\text{V}$

Q. The length of a potentiometer wire $1200\text{cm}$ and it carries a current of $60\text{mA}$. For a cell of emf $5\text{V}$ and internal resistance of $20\Omega$, the null point on it is found to be $1000\text{cm}$. The resistance of whole wire is:

1. $80\Omega$
2. $120\Omega$
3. $60\Omega$
4. $100\Omega$

Q. In a potentiometer wire experiment, the emf of a battery in the primary circuit is $20$ Volt and its internal resistance is $5\Omega$. There is a resistance box (in series with the battery and the potentiometer wire) whose resistance can be varied from $120\Omega$ to $170\Omega$. Resistance of the potentiometer wire is $75\Omega$. The following potential difference can not be measured using this potentiometer

1. $5\text{V}$
2. $6\text{V}$
3. $7\text{V}$
4. $8\text{V}$

Q. A potentiometer wire has length $10\text{m}$ and resistance $10\Omega$. It is connected to a battery of emf $11\text{V}$ and internal resistance $1\Omega$, then the potential gradient in the wire is

1. $10\text{V/m}$
2. $1\text{V/m}$
3. $0.1\text{V/m}$
4. none

Q. The voltage across a bulb is decreased by $2\%.$ Assuming that the resistance of the filament remains unchanged the power of the bulb will

1. decrease by 4%
2. decrease by 2%
3. increase by 4%
4. increase by 2%

Q. A potentiometer wire has a length of $10\text{m}$ and resistance $4\Omega {\text{m}}^{-1}$. An accumulator of emf $2\text{V}$ and a resistance box are connected in series with it. Calculate the resistance to be introduced in the box to get a potential gradient of $0.1\text{V/m}$.

1. $20\Omega$
2. $30\Omega$
3. $40\Omega$
4. $50\Omega$

Q. A 100 W bulb $B_1$ and two 60 W bulbs $B_2$ and $B_3$ are connected to a 250 V source as shown in figure. $W_1$, $W_2$and $W_3$are the output powers of the bulbs $B_1$, $B_2$ and $B_3$ respectively then

1. W₁ > W₂ = W₃
2. W₁ > W₂ > W₃
3. W₁ < W₂ = W₃
4. W₁ < W₂ < W₃

Q. Figure below shows a circuit which may be used to compare the resistance $R$ of an unknown resistor with a $100\Omega$ standard. The distances $l$ from one end of the potentiometer slider wire to the balance point are 400 mm and 588 mm when X is connected to Y and Z respectively. The length of the slide is 1.00 m. What is the value of resistance R?

1. $32\Omega$
2. $147\Omega$
3. $47\Omega$
4. $68\Omega$

Q. A potentiometer wire of length $10\text{m}$ and resistance $30\text{ohm}$ is connected in series with a battery of emf $2.5\text{V}$, internal resistance $5\text{ohm}$ and external resistance $R$. If the fall of potential along the potentiometer wire is $50\text{mV/m}$ the value of $R$ in $\Omega$ is

Q. In the circuit diagram, all the bulbs are identical. Which bulb will be the brightest?

1. A
2. B
3. C
4. D

Q.

How does the strength of the magnetic field produced by a current-carrying circular coil depend on the number of turns in the coil?

Q. A potentiometer wire, $4\text{m}$ long and resistance $12\Omega$ , is connected in series with a resistance of $1988\Omega$ and a cell of emf $2\text{V}$. What is the potential gradient along the wire ?

1. $0.002\frac{\text{V}}{\text{m}}$
2. $0.004\frac{\text{V}}{\text{m}}$
3. $0.01\frac{\text{V}}{\text{m}}$
4. $0.003\frac{\text{V}}{\text{m}}$

Q. A battery is connected to a potentiometer and the balance point is obtained at $84\text{cm}$ along the wire. When its terminals are connected by a $5\Omega$ resistor, the balance point changes to $70\text{cm}$.

$\left(i\right)$ Calculate the internal resistance of the cell.

​​​​​​​$[$1 Mark$]$

1. $4\Omega$
2. $2\Omega$
3. $5\Omega$
4. $1\Omega$

Q. $n$ identical light bulbs, each designed to draw $P$ power from a certain voltage supply, are joined in series across that supply. The total power which they will draw is

1. $nP$
2. $P$
3. $P/n$
4. $P/n^2$

Q. Three bulbs $B_1,B_2$ and $B_3$ are connected to the mains as shown in the figure. How will the brightness of bulb $B_1$ be affected if $B_2$ or $B_3$ are disconnected from the circuit?

1. Bulb $B_1$ becomes brighter
2. Bulb $B_1$ becomes dimmer
3. No change occurs in the brightness
4. Bulb $B_1$ becomes brighter if bulb $B_2$ is disconnected and dimmer if bulb $B_3$ is disconnected

Q. a circuit containing inductor, bulb and battery has a switch, the bulb will become suddenly bright if

1. Contact is made or broken
2. Contact is made
3. Contact is broken
4. Won't become bright at all

Q. A potentiometer wire of $4\text{m}$ long having resistance $12\Omega$ is connected in series with a resistance of $1988\Omega$ and a cell of emf $2\text{V}$. What is the potential gradient along the wire ?

1. $0.002\text{V/m}$
2. $0.004\text{V/m}$
3. $0.001\text{V/m}$
4. $0.003\text{V/m}$

Q. $AB$ is a potentiometer wire of length $100cm$ and its resistance is $10\Omega$. It is connected in series with a battery of emf $2V$ and resistance $40\Omega$. If a source of unknown emf $E$ is balanced by $40cm$ length of the potentiometer wire, the value of $E$ is

1. $0.8V$
2. $1.6V$
3. $0.08V$
4. $0.16V$