Mixed Combination of Cells

Q. A battery of emf $10V$ and internal resistance $3\Omega$ is connected to a resistor. If the current in the circuit is $0.5A$, what is the resistance of the resistor? What is the terminal voltage of the battery when the circuit is closed?

Q.

Why should a voltmeter have a high resistance and an ammeter a low resistance?

Q.

A wire of $1\Omega$ has a length of $1m$. It is stretched till its length increases by $25\%$. The percentage change in resistance to the nearest integer is:

1. $25\%$

2. $12.5\%$

3. $76\%$

4. $56\%$

Q. A capacitor of $4\mu F$ is connected as shown in the circuit (figure). The internal resistance of the battery is $0.5\Omega$. The amount of charge on the capacitor plates will be

1. $8\mu C$
2. $0$
3. $16\mu C$
4. $4\mu C$

Q.

What are the types of Amplifier?

Q. Knee voltage of threshold voltage values for Si and Ge diodes are 0.7 V and 0.3 V respectively. Let a Si and a Ge diode are connected in a circuit as shown in the figure. Then, output voltage is

1. 12 V
2. 111.3 V
3. 1.7 V
4. 110 V

Q. In an $LCR$ circuit the potential difference between the terminals of the inductance is $60V$, between the terminals of the capacitor is $30V$ and that between the terminals of resistance is $40V$. The supply voltage will be equal to ______.

1. $10V$
2. $130V$
3. $50V$
4. $70V$

Q.

What is the resistance of an ideal voltmeter?

Q. The resistance of the filament of a lamp increases with the increase in temperature. $A$ lamp rated
$100W,$ $220V$ is connected across $220V$ power supply. If the voltage drops $10\%$ then the power
of lamp will be

1. Between $81W$ and $90W$
2. $81W$
3. $90W$
4. Between $90W$ and $100W$

Q. What happens if the galvanometer and cell are interchanged at the balance point of the bridge? Would the galvanometer show any current? Please explain thoroughly.

Q. In the circuit shown below, the cells A and B have negligible resistance. For $V_A=12V,R_1=500\Omega$ and $R=100\Omega$, the galvanometer (G) shows no deflection. The value of $V_B$ is:

1. 4V
2. 2V
3. 6V
4. 12V

Q. Eels are able to generate current with biological cells called electroplaques. The electroplaques in an eel are arranged in 100 rows, each row stretching horizontally along the body of the fish containing 5000 electroplaques. The arrangement is suggestively shown below. Each electroplaques has an emf of 0.15 V and internal resistance of 0.25$\Omega$. The water surrounding the eel completes a circuit between the head and its tail. If the water surrounding it has a resistance of 500 ohm, the current an eel can produce in water is about

1. 1.5 A
2. 3.0 A
3. 15 A
4. 30 A

Q.

Applications of ohms law used in daily life?

Q.

An ideal cell of $emf10V$ is connected in circuit shown in figure. Each resistance is $2\Omega$. The potential difference $\left(inV\right)$ across the capacitor when it is fully charged is _______.

Q. In the figure shown, the equivalent capacitance between ${}^{\prime }{A}^{\prime }$ and ${}^{\prime }{B}^{\prime }$ is:

1. $3.75F$
2. $2F$
3. $21F$
4. $16F$

Q. An infinite ladder network is constructed with $1\Omega$ and $2\Omega$ resistors as shown. The effective resistance between $A$ and $B$ is

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

Q.

You are given several identical resistors each of value 10ohm and each capable of 1A. It is required to make a suitable combination of these two resistances to produce a resistance of 5ohm which can carry a current of4A . The minimum number of resistors required for this job?

Q. A charged particle having drift velocity of $7.5\times {10}^{-4}{\text{ms}}^{-1}$ in an electric field of $3\times {10}^{-10}{\text{Vm}}^{-1}$, has a mobility of (in${\text{m}}^2{\text{V}}^{-1}{\text{s}}^{-1}$)

1. $2.25\times {10}^{15}$
2. $2.25\times {10}^{-15}$
3. $2.5\times {10}^{-6}$
4. $2.5\times {10}^6$

Q.

Calculate the resistance of filament of $100\mathrm{W},220\mathrm{V}$ electric bulb.

Q.

Under what conditions is Ohms law applicable?

Q. In the adjoining circuit, the battery $E_1$ has as emf of 12 volt and zero internal resistance, while the battery E has an emf of 2 volt. If the galvanometer reads zero, then the value of resistance X ohm is

1. 100
2. 300
3. 500
4. 200

Q. An inductor of reactance \(1~\Omega\) and a resistor of \(2~\Omega\)are connected in series to the terminals of a \(6~𝑉(𝑟𝑚𝑠)\) AC source.
The power dissipated in the circuit is:

Q. To get maximum current in a resistance of $3\Omega$ one can use n rows of m cells connected in parallel. If the total no. of cells is 24 and the internal resistance of a cell is$0.5\Omega$ then

1. m = 12, n = 2
2. m = 8, n = 4
3. m = 2, n = 12
4. m = 6, n = 4

Q.

The resistance of the meter bridge AB in the given figure is $4\mathrm{\Omega }$ with a cell of $emf=0.5V$ and rheostat resistance $R_h=2\mathrm{\Omega }$ the null point is obtained at some point J. When the cell is replaced by another one of emf $\epsilon ={\epsilon }_2$ the same null point J is found for $R_h=6\mathrm{\Omega }$. The emf ${\epsilon }_2$is;

1. $0.3V$

2. $0.5V$

3. $0.4V$

4. $0.6V$

Q. An air capacitor is connected to a battery. The effort of filling the space between the plates with a dielectric is to increase

1. the electric field and the capacitance
   
2. the potential difference and the electric field
   

3. the charge and the capacitance

4. the charge and the potential difference
   

Q. In figure, at steady state what is the potential difference between the points $A$, $B$ and between $B$, $C$ respectively ?

1. $100V$ both
2. $V_{AB}=50V,V_{BC}=50V$
3. $V_{AB}=25V,V_{BC}=75V$
4. $V_{AB}=75V,V_{BC}=25V$

Q. You are given 48 cells each of emf 2 V and internal resistance 1 ohm. How will you connect them so that the current through an external resistance of 3 ohm is the maximum?

1. 8 cells in series 6 such groups in parallel
2. 16 cells in series 3 such groups in parallel
3. 24 cells in series 2 such groups in parallel
4. 12 cells in series 4 such groups in parallel

Q. A solenoid is connected to a battery so that a steady current flow through it. If an iron core is inserted into the solenoid, will the current increase or decrease? Explain.

Q. A capacitor when filled with a dielectric \(k=3\) has charge \(Q_0\), voltage \(V_0\) and field \(E_0\). If the dielectric is replaced with another one having \(k=9\), the new values of charge, voltage and field will be respectively

Q.

Derive an expression for electric power connecting:

(a) Current and resistance

(b) Current and potential difference

(c)Potential difference and resistance