AIPMT 2009 | Alternating Current Question 49 | Physics

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AIPMT 2009

MCQ (Single Correct Answer)

-1

Power dissipated in an LCR series circuit connected to an A.C. source of emf $$\varepsilon $$ is

$${{{\varepsilon ^2}\sqrt {{R^2} + {{\left( {L\omega - {1 \over {\omega }}} \right)}^2}} } \over R}$$

$${{{\varepsilon ^2}\sqrt {{R^2} + {{\left( {L\omega - {1 \over {C\omega }}} \right)}^2}} } \over R}$$

$${{{\varepsilon ^2}R} \over {\sqrt {{R^2} + {{\left( {L - {1 \over {C\omega }}} \right)}^2}} }}$$

$${{{\varepsilon ^2}R} \over {\left[ {{R^2} + {{\left( {L\omega - {1 \over {C\omega }}} \right)}^2}} \right]}}$$

AIPMT 2008

MCQ (Single Correct Answer)

-1

In an a.c. circuit the e.m.f. ($$\varepsilon $$) and the current

(i) at any instant are given respectively by
$$\varepsilon $$ = E₀sin$$\omega $$t, $$i$$ = $$I$$₀sin($$\omega $$t $$-$$ $$\phi $$)

The average power in the circuit over one cycle of a.c. is

$${{{E_0}{I_0}} \over 2}\cos \phi $$

$${{E_0}{I_0}}$$

$${{{E_0}{I_0}} \over 2}$$

$${{{E_0}{I_0}} \over 2}\sin \phi $$

AIPMT 2007

MCQ (Single Correct Answer)

-1

A transformer is used to light a 100 W and 110 V lamp from a 220 V mains. If the main current is 0.5 amp, the efficiency of the transformer is approximately

50%

90%

10%

30%

AIPMT 2007

MCQ (Single Correct Answer)

-1

The primary and secondary coils of a transformer have 50 and 1500 turns respectively. If the magnetic flux $$\phi $$ linked with the primary coil is given by $$\phi $$ = $$\phi $$₀ + 4t, where $$\phi $$ is webers, t is time in seconds and $$\phi $$₀ is a constant, the output voltage across the secondary coil is

120 volt

220 volts

30 volts

90 volts.

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