Question:
An engine delivers \(1000\text{ watt}\) of power with \(80\%\) efficiency. The input power is
An engine delivers \(1000\text{ watt}\) of power with \(80\%\) efficiency. The input power is
Show Hint
Efficiency \(=\frac{\text{Output power}}{\text{Input power}}\). Always convert percentage efficiency into decimal before calculation.
Updated On: May 7, 2026
- \(800\text{ W}\)
- \(1000\text{ W}\)
- \(1250\text{ W}\)
- \(1500\text{ W}\)
Show Solution
Verified By Collegedunia
The Correct Option is C
Solution and Explanation
We are given output power:
\[
P_{\text{out}}=1000\text{ W}.
\]
Efficiency is:
\[
\eta=80\%.
\]
Convert percentage into decimal:
\[
\eta=\frac{80}{100}=0.8.
\]
Efficiency is defined as:
\[
\eta=\frac{P_{\text{out}}}{P_{\text{in}}}.
\]
We need to find input power:
\[
P_{\text{in}}.
\]
Rearrange the formula:
\[
P_{\text{in}}=\frac{P_{\text{out}}}{\eta}.
\]
Substitute the values:
\[
P_{\text{in}}=\frac{1000}{0.8}.
\]
\[
P_{\text{in}}=1250\text{ W}.
\]
Therefore, the input power is:
\[
1250\text{ W}.
\]
Was this answer helpful?
0
0
Top AP ECET Physics Questions
- Three rods of same dimensions have thermal conductivities 3 K, 2 K and K. They are arranged as shown below:What will be the temperature T of the junction?
- A ball of mass 0.6 kg attached to a light inextensible string rotates in a vertical circle of radius 0.75 m such that it has a speed of $ 5\text{ }m{{s}^{-1}} $ when the string is horizontal. Tension in string when it h horizontal on other side is $ (g=10m{{s}^{-}}2) $
- Three resistances of equal values are arranged in four different configurations as shown below. Power dissipation in the increasing order is
- Four resistors $A, B, C$ and $D$ form a Wheatstones bridge. The bridge is balanced, when $C=100 \Omega$. If $A$ and $B$ are interchanged, the bridge balances for $C=121 \Omega$. The value of $D$ is
- A parallel plate capacitor consists of two circular plates each of radius $2 \,cm$, separated by a distance of $0.1 \,mm$. If the potential difference across the plates is varying at the rate of $5 \times 10^{6} Vs ^{-1}$, then the value of displacement current is
View More Questions
Top AP ECET work, energy and power Questions
- A ball of mass 0.6 kg attached to a light inextensible string rotates in a vertical circle of radius 0.75 m such that it has a speed of $ 5\text{ }m{{s}^{-1}} $ when the string is horizontal. Tension in string when it h horizontal on other side is $ (g=10m{{s}^{-}}2) $
- A body of mass \(2\text{ kg}\) changes its velocity from \((3\hat{i}-4\hat{j})\text{ m/s\) to \((6\hat{j}+2\hat{k})\text{ m/s}\). What is the change in kinetic energy of the body?}
- At her maximum height a girl in a swing is \(3\text{ m}\) above the ground and at the lowest point she is \(2\text{ m}\) above the ground. Her maximum velocity is
- A body of mass \(1\ \text{kg}\) starts moving from rest under the action of a force which varies with displacement as \(F=2x+5\) in newtons. The work done by this force to displace the body from \(x=0\) to \(x=2\ \text{m}\) is
- The potential energy of a particle is given by \(U(x)=20+(x-2)^2\), where \(U\) is in joules and \(x\) is in meters. The minimum potential energy and the position where it occurs are
View More Questions
Top AP ECET Questions
- The sum of the four digit even numbers that can be formed with the digits 0,3,5,4 with out repetition is
- Thermal decomposition of $HCOOH$ is a first order reaction and the rate constant at T(K) is $4.606 \times 10^{-3}\, s^{-1}$. The time required to decompose $90\%$ of initial quantity of $HCOOH$ at $T(K)$ in seconds is
- Three rods of same dimensions have thermal conductivities 3 K, 2 K and K. They are arranged as shown below:What will be the temperature T of the junction?
- To which group and period does the element belong if the electronic configuration of an element in its $-2$ oxidation state is $1s^{2} 2s^{2} 2p^{6} 3s^{2} 3p^{6}$ ?
- A ball of mass 0.6 kg attached to a light inextensible string rotates in a vertical circle of radius 0.75 m such that it has a speed of $ 5\text{ }m{{s}^{-1}} $ when the string is horizontal. Tension in string when it h horizontal on other side is $ (g=10m{{s}^{-}}2) $
View More Questions