MCQOPTIONS
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MCQOPTIONS
This section includes 10 Mcqs, each offering curated multiple-choice questions to sharpen your Physics knowledge and support exam preparation. Choose a topic below to get started.
| 1. |
In a step-down transformer, the number of turns in the secondary coil is 20 and the number of turns in the primary coil is 100. If the voltage applied to the primary coil is 120 V, then what is the voltage output from the secondary coil? |
| A. | 24 V |
| B. | 12 V |
| C. | 6 V |
| D. | 18 V |
| Answer» B. 12 V | |
| 2. |
A transformer is used to light 100 W 25 volt lamp from 250 Volt ac mains. The current in the main cable is 0.5 A. Calculate the efficiency of the transformer. |
| A. | 50% |
| B. | 60% |
| C. | 90% |
| D. | 80% |
| Answer» E. | |
| 3. |
Current remains unchanged in a transformer. |
| A. | True |
| B. | False |
| Answer» C. | |
| 4. |
A transformer has an efficiency of 60% and works at 5kW. If the secondary voltage is 150 V, then what is the secondary current? |
| A. | 10 A |
| B. | 20 A |
| C. | 30 A |
| D. | 40 A |
| Answer» C. 30 A | |
| 5. |
Which of the following is usually taken to make the core of a transformer? |
| A. | Aluminum |
| B. | Copper |
| C. | Soft iron |
| D. | Hard iron |
| Answer» D. Hard iron | |
| 6. |
Identify the correct combination for a step-down transformer. |
| A. | k < 1; Vs > Vp, Is > Ip, Ns < Np |
| B. | k > 1; Vs < Vp, Is > Ip, Ns > Np |
| C. | k > 1; Vs > Vp, Is < Ip, Ns > Np |
| D. | k < 1; Vs < Vp, Is > Ip, Ns < Np |
| Answer» E. | |
| 7. |
The efficiency of a transformer is the ratio of output power to input power. |
| A. | True |
| B. | False |
| Answer» B. False | |
| 8. |
Pick out the correct combination for a step-up transformer. |
| A. | k < 1; Vs > Vp, Is > Ip, Ns > Np |
| B. | k > 1; Vs > Vp, Is < Ip, Ns > Np |
| C. | k > 1; Vs > Vp, Is > Ip, Ns > Np |
| D. | k < 1; Vs < Vp, Is > Ip, Ns > Np |
| Answer» C. k > 1; Vs > Vp, Is > Ip, Ns > Np | |
| 9. |
Identify the expression for transformation ratio from the following. |
| A. | k = \(\frac {V_s}{V_p}=\frac {I_s}{I_p}=\frac {N_s}{N_p}\) |
| B. | k = \(\frac {V_s}{V_p}=\frac {I_s}{I_p}=\frac {N_p}{N_s}\) |
| C. | k = \(\frac {V_s}{V_p}=\frac {I_p}{I_s}=\frac {N_s}{N_p}\) |
| D. | k = \(\frac {V_p}{V_s}=\frac {I_s}{I_p}=\frac {N_s}{N_p}\) |
| Answer» D. k = \(\frac {V_p}{V_s}=\frac {I_s}{I_p}=\frac {N_s}{N_p}\) | |
| 10. |
Which among the following is true about transformers? |
| A. | Transformers are used to convert low alternating voltage to a high alternating voltage |
| B. | Transformers are used to convert low alternating current to a high alternating current |
| C. | Transformers are based on the phenomena of mutual electric field |
| D. | Transformers are used only for low alternating voltage |
| Answer» B. Transformers are used to convert low alternating current to a high alternating current | |