AC Applied to a Resistor

Q.

Express the power of a 100 watt bulb in CGS unit.

Q.

Two resistors of resistance R1 =100±3 and R2 =200±4 .find the equivalent reaisresis in parallel combination

Q.

Why is Q factor important?

Q.

What is a choke coil

Q. In 1 minute, how much energy does a $100W$ electric bulb consumes?

1. $1000J$
2. $6000J$
3. $100J$
4. $600J$

Q. Find the average and rms values of the saw-tooth wave form as shown in figure.


and report the nearest integer of the sum of two.

Q. A series $LCR$ circuit has $L=0.01H,R=10\Omega \text{and}C=1\mu F$ and it is connected to $ac$ voltage of amplitude $\left(Vm\right)50V$. At frequency $60\%$ lower than resonant frequency, the amplitude of current will be approximately

Q. If two resistors of resistances R1 = (4±0.5) ohm and R2 = (16±0.5) ohm are connected in series, find the equivalent resistance with limits of percentage error.

Q.

N resistors each of resistance R are first combined to get minimum possible resistance and then combined to get maximum possible resistance. The ratio of the minimum to maximum resistance is

1. 1/N

2. N²

3. N

4. 1/N²

Q. Find the $rms$ value of the Sawtooth voltage of peak value $V_0$ per cycle, for which the time function is shown in figure.

1. $V_0$
2. $\frac{V_0}{\sqrt{2}}$
3. $\frac{V_0}{\sqrt{3}}$
4. $\frac{V_0}{2}$

Q. A resistance of $20\Omega$ is connected to a source of alternating current rated $110\text{V},50\text{Hz}$. Find the time taken by the current to change from its first maximum value to the consecutive rms value.

1. $5.5\text{ms}$
2. $4.5\text{ms}$
3. $2.5\text{ms}$
4. $3.5\text{ms}$

Q. Three equal resistance each of 10 ohm are connected (2 in parallel, and 1 in series). The maximum safe power consumed by each resistor is 20W. The maximum safe power consumed by the combination is?

Q.

What is the inductive resistance formula?

Q.

The presence and direction of flow of current is detected by a device called ………. (ammeter/ galvanometer).

Q.

An ac source is connected to a resistive circuits. Which of the following is true

1. Current leads the voltage and both are in same phase

2. Current lags behind the voltage and both are in same phase

3. Current and voltage are in same phase

4. Any of the above may be true depending upon the value of resistance

Q. The circuit shown in figure consists of a battery of emf $E$ , resistances $R_1$ and $R_2$ inductances $L$ and a two way switch $ABC$. Initially $A$ is connected to $B$ for a long time and at $t=0$ $A$ is connected to $C$. Then,

1. The current through inductor when the switch is in position $B$ is$\frac{E}{R_1}$
2. The current through inductor when the switch is in position $B$ is$\frac{E}{R_2}$
3. The total heat produced in $R_2$ after the switch is thrown to $C$ is$\frac{L{E}^2}{2R_2^2}$
4. The total heat produced in $R_2$ after the switch is thrown to $C$ is $\frac{L{E}^2}{2R_1^2}$

Q. Show that time constant of R-C circuit has dimensions of time

Q.

Two terminals of a cell of emf 2.5 V are connected to the two ends of the 10 ohm resistance coil. If the current in the circuit is 0.2 A, then the internal resistance of the cell is

1. 3.2 ohm

2. 4.5 ohm

3. 2 ohm

4. 2.5 ohm

Q. A coil of resistance $300\Omega$ and inductance $1.0\text{H}$ is connected across an alternating voltage of frequency $\frac{300}{2\pi }\text{Hz}$. Calculate the phase difference between the voltage and current in the circuit.

1. $\frac{\pi }{3}$
2. $\frac{\pi }{6}$
3. $\frac{\pi }{4}$
4. $\pi$

Q. The phasor diagram of current and voltage for an AC circuit is shown in the figure. The components of the circuit will be -

1. only resistor
2. only inductor
3. only capacitor
4. both resistor and inductor

Q. A $10\Omega$ electric iron is connected to $120V,60Hz$ wall outlet. What is the peak current through the electric iron?

1. $12A$
2. $12\sqrt{2}A$
3. $10\sqrt{2}A$
4. 10 A

Q. Find the resistance between the points $A$ and $B$ .

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

Q. A longitudinal wave is represented by $x=x_{0}sin2\pi (nt-\frac{x}{\lambda })$. The maximum particle velocity will be four times the wave velocity if:

1. $\lambda =\frac{\pi x_0}{4}$
2. $\lambda =2\pi x_0$
3. $\lambda =\frac{\pi x_0}{2}$
4. $\lambda =4\pi x_0$

Q. 43.A coil having zero resistance is connected in series with a 90ohm resistance and the combination in connected to 120V , 60Hz A voltmeter reads 36V across the resistance and 114V across the coil the self inductance of the coil is 1)0.076H 2)0.76H 3)7.6H 4)76H

Q. In an electrical circuit, two resistors of $2\Omega$ and $4\Omega$ are connected in series to $6\text{V}$ battery. The heat dissipated by the $4\Omega$ resistor in $5\text{s}$ will be -

1. $50\text{J}$
2. $30\text{J}$
3. $20\text{J}$
4. $40\text{J}$

Q. The peak voltage of an ac supply is $300V$. What is the rms voltage?

Q. 10. I1 and i2 are the current recorded in the two branches of two circuits as shown in figure . curve shown in figure are pulsating . value of the ratio of RMS of first:mean of second

Q.

Find the resistance between a and b in the circuit given below:

1. 9Ω

2. 12Ω

3. 6Ω

4. 3Ω

Q. Voltage applied to an $AC$ circuit and current flowing in it is given by
$V=200\sqrt{2}\sin \left(\omega t+\frac{\pi }{4}\right)$ and $i=-\sqrt{2}\cos \left(\omega t+\frac{\pi }{4}\right)$
The power consumed in the circuit will be

1. $200W$
2. $400W$
3. $200\sqrt{2}W$
4. None of these

Q. How to find impedance of a circuit in which two voltage of 120V and 90V are connected in series and a current of 3A is flowing?