WAEC Physics questions: Simple a.c. circuits

9 questions with answers and explanations. Tap an option to check yourself.

1. Question 1· Simple a.c. circuits· WAEC

   The reactance of a capacitor decreases when the frequency of the supply

   • Astays the same
   • Bdecreases
   • Cincreases
   • Dbecomes zero

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2. Question 2· Simple a.c. circuits· WAEC

   Find the reactance of a 0.7 H inductor on a 50 Hz supply. [π = 22/7]

   • A110 Ω
   • B220 Ω
   • C35 Ω
   • D440 Ω

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3. Question 3· Simple a.c. circuits· WAEC

   The frequency of the public electricity supply in Nigeria is

   • A50 Hz
   • B60 Hz
   • C100 Hz
   • D240 Hz

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4. Question 4· Simple a.c. circuits· WAEC

   An alternating current has a peak value of 10√2 A. Its r.m.s. value is

   • A10 A
   • B20 A
   • C14.1 A
   • D5 A

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5. Question 5· Simple a.c. circuits· WAEC

   The peak value of an alternating current is 10√2 A. Find its r.m.s. value.

   • A14.1 A
   • B20 A
   • C10 A
   • D5 A

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6. Question 6· Simple a.c. circuits· WAEC

   The unit of inductive reactance is the

   • Aohm
   • Bhenry
   • Cfarad
   • Dhertz

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7. Question 7· Simple a.c. circuits· WAEC

   In a purely resistive a.c. circuit, the current and voltage are

   • A180° out of phase
   • B90° out of phase
   • Cin phase
   • Dalways zero

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8. Question 8· Simple a.c. circuits· WAEC

   In a purely inductive a.c. circuit, the current

   • Ais always zero
   • Bleads the voltage by 90°
   • Cis in phase with the voltage
   • Dlags the voltage by 90°

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9. Question 9· Simple a.c. circuits· WAEC

   The r.m.s. value of an a.c. voltage with peak 340 V is about

   • A240 V
   • B340 V
   • C480 V
   • D170 V

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   Explanation and discussion