Alternating Current

Bihar Board Class 12 · Physics · 41 past questions

1. Q1 2026 Set A

   Which quantity decreases in step-down transformer ?

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2. Q2 2026 Set A

   In an ac circuit of capacitance the current from potential difference is

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3. Q3 2026 Set A

   A capacitor is a perfect insulator for

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4. Q4 2026 Set A

   The voltage of domestic ac is 220 V. What does this represent ?

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5. Q5 2026 Set A

   Choke coil works on the principle of

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6. Q6 2025 Set D

   The peak value of an alternating current is 10 $A$. Its root mean square value will be

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7. Q7 2025 Set D

   In a purely inductive circuit, the power factor is

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8. Q8 2025 Set D

   In an a.c. circuit containing only capacitor, the phase difference between current and voltage is

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9. Q9 2025 Set D

   In resonance condition, the frequency of $L$-$C$ circuit is

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10. Q10 2025 Set D2023 Set F

    In a step-up transformer, the value of current in secondary compared to the primary coil is

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11. Q11 2024 Set A

    What value of alternating current is measured by hot wire ammeter ?

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12. Q12 2024 Set A

    Unit of reactance is

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13. Q13 2024 Set A

    Mean value of alternating current in a full cycle is

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14. Q14 2024 Set A

    If the phase difference between alternating current and e.m.f. is $\phi$, then the value of power factor is

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15. Q15 2024 Set A

    In $AC$ circuit, power is lost in only

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16. Q16 2024 Set A

    An alternating electric current is represented by equation $I = 0.6\sin 100\pi t$. The frequency of…

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17. Q17 2023 Set F

    The phase-difference between current and voltage in only capacitive alternating current circuit is

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18. Q18 2023 Set F

    The impedance of L-R circuit is

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19. Q19 2023 Set F

    For resonance condition in any L-C-R circuit, the phase-difference between applied voltage and current is

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20. Q20 2022 Set I

    The expression for real average power in an alternating current circuit is

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21. Q21 2022 Set I

    Power factor is equal to

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22. Q22 2022 Set I

    Phase difference in $(L\text{-}R)$ circuit is

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23. Q23 2022 Set I

    Transformation ratio in transformer is

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24. Q24 2022 Set I

    Dimensional formula of R.C. is

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25. Q25 2022 Set I

    Which of the following is correct for step-up transformer ?

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26. Q26 2022 Set I

    Inductive reactance for direct current is

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27. Q27 2022 Set I

    Inductive reactance is

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28. Q28 2021 Set A

    The relation between r.m.s. value of alternating current ($I_{r.m.s.}$) and peak value of alternating current…

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29. Q29 2021 Set A

    Inductive reactance offered by an inductor of inductance $L$ in ac circuit of angular frequency $\omega$ is

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30. Q30 2021 Set A

    Which of the following relations is correct for power factor ?

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31. Q31 2021 Set A

    Which of the following is correct for transformer ?

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32. Q32 2021 Set A

    Capacitive reactance is

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33. Q33 2019

    In a step-up transformer, no, of turns in primary and secondary coils are $N_1$ and $N_2$, then

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34. Q34 2019

    The power factor of L-R circuit is

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35. Q35 2019

    In an alternating current circuit, the phase difference between curren I and voltage $\phi$, then the Wattles…

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36. Q36 2019

    The ratio of root mean (rms) value and peak value of alternative current is

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37. Q37 2019

    Establish the relation between mean value and peak value of AC.

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38. Q38 2019

    What are reactance and impedance in alternative current circuit?

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39. Q39 2017

    If the equation of an electric current is $I = 0.6\sin 100\pi t$, the frequency of electric current is-

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40. Q40 2017

    The unit of reactance is-

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41. Q41 2017

    The relation between peak current $I_0$ and root mean square current I rms is-

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