Power

Q. If the power of a body is given by $P=xv$, where $v$ is the velocity of the body then the dimension of $x$ is

1. $\left[ML{T}^{-2}\right]$
2. $\left[ML{T}^2\right]$
3. $\left[M{L}^2{T}^{-2}\right]$
4. $\left[M^{2}L{T}^2\right]$

Q. A $2\mu \text{F}$ capacitor is changed as shown in the figure. The percentage of its stored energy dissipated after the switch $S$ is turned to the position $2$ is,

1. $75\%$
2. $0\%$
3. $20\%$
4. $80\%$

Q. If an electric heater consumes electricity at the rate of $500W$ and the potential difference between the two terminals of the electric circuit is $250V$, calculate the electric current passing through the heater and resistance of it respectively.

1. $4A,125\Omega$
2. $2A,125\Omega$
3. $4A,250\Omega$
4. $2A,250\Omega$

Q. A (3i + 4j) N force acting on a body displaces it by (3i + 4j) m. The work done by the force is

1. 25 J
2. 7 J
3. 5 J
4. zero

Q. A total of Q charge flows from resistance R in time interval T such that current vs time graph is obtained as shown in figure. The heat generated in resistance is:

1. $I_0^{2}RT$
2. $\frac{I_0^{2}RT}{3}$
3. $\frac{I_0^{2}RT}{2}$
4. $\frac{I_0^{2}RT}{4}$

Q. An rms voltage of $110\text{V}$ is applied across a series circuit having a resistance $11\Omega$ and an impedance $22\Omega$. The power consumed is

1. $275\text{W}$
2. $366\text{W}$
3. $550\text{W}$
4. $1100\text{W}$

Q.
$i=15\sin \omega t+20\cos \omega t$.
Alternating current $i$ is passed through a resistance of $8\Omega$. Find the heat developed across R in 10 seconds.

1. $25\times {10}^3$ J
2. $125\times {10}^2$ J
3. $625\times {10}^2$ J
4. $5\times {10}^4$ J

Q. Four identical bulbs each rated $100\text{watt}$ , $220\text{volts}$ are connected across a battery as shown. The total electric power consumed by the bulbs (in $\text{watt}$) is:

Q. A voltage of peak value $283\text{V}$ and varying frequency is applied to a series $LCR$ combination in which $R=3\Omega ,L=25\text{mH}$ and $C=400\mu \text{F}$. Then, the frequency $\left(\text{in Hz}\right)$ of the source at which maximum power is dissipated in the above circuit, is

1. $52.5$
2. $50.3$
3. $53.1$
4. $56.7$

Q. A battery is charged at a potential of $15V$ for $8h$ when the current flowing is $10A$. The battery on discharge supplies a current of $5A$ for $15h$. The mean terminal voltage during discharge is $14V$. The watt-hour efficiency of the battery is

1. $82.5\%$
2. $80\%$
3. $90\%$
4. $87.5\%$

Q. Graph of V vs I is given in figure. Its ln(P) vs ln(I) graph will be

1. 
2. 
3. 
4.