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COMEDK2022PhysicsAlternating Current

A DC ammeter and a hot wire ammeter are connected to a circuit in series. When a direct current is passed through circuit, the DC ammeter shows 6 ~A . When AC current flows through circuit, what is the average readings in DC ammeter and the AC ammeter, if DC and AC currents flow simultaneously through the circuit?

Options

  1. ADC =6 ~A , AC =10 ~A
  2. BDC =3 ~A , AC =5 ~A
  3. CDC =5 ~A , AC =8 ~A
  4. DDC =2 ~A , AC =3 ~A

Correct answer

A. DC =6 ~A , AC =10 ~A

Step-by-step solution

A DC ammeter measures the average value of the current passing through it. When a DC current I_ DC and an AC current I_ AC (t) = I₀ ( t) flow simultaneously, the total current is I(t) = I_ DC + I₀ ( t) . The reading of the DC ammeter is the average value of the total current over a full cycle of the AC component. Since the average value of a sinusoidal current over a full cycle is zero, the DC ammeter reads I_ DC = 6 A . A hot wire ammeter measures the root mean square (RMS) value of the current. The total current

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