COMEDK · Physics · 23. Alternating Current
A step down transformer is used to reduce the main supply of 220 V to 10 V . If the primary draws 5 A and secondary 88 A current, calculate the efficiency of the transformer.
- A \(40 \%\)
- B \(60 \%\)
- C \(80 \%\)
- D \(45 \%\)
Answer & Solution
Correct Answer
(C) \(80 \%\)
Step-by-step Solution
Detailed explanation
\(e_p=220 \mathrm{~V}, e_s=10 \mathrm{~V}, I_p=5 \mathrm{~A}\) and \(I_s=88 \mathrm{~A}\) Input power, \(P_i=e_P \times I_P=220 \times 5=1100 \mathrm{~W}\) Output power, \(P_o=e_s \times I_s=10 \times 88=880 \mathrm{~W}\) Efficiency, \(\eta=\frac{P_0}{P_1}=\frac{880}{1100}=0.8\)…
See the Complete Solution
Get step-by-step explanations for this and 2.5 Lakh+ more JEE, NEET & CET questions.
- Unlock all solutions
- Practice the full chapter
- Track accuracy across PYQs
4.8 rated on Google Play · 14,000+ reviews
More questions from Physics
- When a particular wave length of light is used the focal length of a convex mirror is found to be \(10 \mathrm{~cm}\). If the wave length of the incident light is doubled keeping the area of the mirror constant, the focal length of the mirror will be:COMEDK 2024 Easy
- Wires made of iron and silicon are cooled from \(50^{\circ} \mathrm{C}\) to \(30^{\circ} \mathrm{C}\), thenCOMEDK 2012 Easy
- Joule second is the unit ofCOMEDK 2024 Easy
- If \(\theta_1\) and \(\theta_2\) be the apparent angles of dip observed in two vertical planes at right angles to each other, then the true angle of \(\operatorname{dip} \theta\) is given byCOMEDK 2023 Easy
- A particle of mass 1 kg is kept on the surface of a uniform sphere of mass 20 kg and radius 1.0 m . The work to be done against the gravitational force between them to take the particle away from the sphere isCOMEDK 2024 Easy
- A particle is moving eastward with a velocity \(5 \mathrm{~ms}^{-1}\). In \(10 \mathrm{~s}\) the velocity changes to \(5 \mathrm{~ms}^{-1}\) northwards. The average acceleration in this time isCOMEDK 2012 Medium
More PYQs from COMEDK
- \(\int \dfrac{(x-1)}{(x+1)^3} e^x d x=P(x)+c\) then \(P(x)=\)COMEDK 2025 Medium
- For a reaction, \(A+B \longrightarrow C+D\),
If the concentration of \(A\) is doubled without altering the concentration of \(B\), the rate gets double(d)If the concentration of \(B\) is increased by nine times without altering the concentration of \(A\), the rate gets triple(d)The order of the reaction isCOMEDK 2018 Medium - When the combustion of one molecule of liquid heptane is carried out at a constant temperature ' \(T\) ', the difference between \(\Delta H^o\) and \(\Delta U^o\) is equal to:COMEDK 2025 Medium
- A solid S is made from a cylinder surmounted by a hemisphere on top with both its circular faces sharing a common centre. The radius of cylinder and radius of hemisphere are \(x \mathrm{~cm}\). The height of the cylinder is \((20-4 x) \mathrm{cm}\) and the volume of S is \(V=\dfrac{1}{3} \pi y\). Find the maximum value of \(y\).COMEDK 2025 Medium
- In a nuclear fusion reaction, two nuclei, \(A\) and \(B\) fuse to produce a nucleus \(C\), releasing an amount of energy \(\Delta \mathrm{E}\) in the process. If the mass defects of the three nuclei are \(\Delta M_A, \Delta M_B\) and \(\Delta M_C\) respectively, then which of the following relations is true? ( \(c\) is the speed of light).COMEDK 2025 Medium
- ............ is unstable at cooking temperature, whereas the control of sweetness of food is difficult while using .........COMEDK 2022 Easy