1
AIPMT 2008
+4
-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
A
$${{{E_0}{I_0}} \over 2}\cos \phi$$
B
$${{E_0}{I_0}}$$
C
$${{{E_0}{I_0}} \over 2}$$
D
$${{{E_0}{I_0}} \over 2}\sin \phi$$
2
AIPMT 2007
+4
-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
A
120 volt
B
220 volts
C
30 volts
D
90 volts.
3
AIPMT 2007
+4
-1
What is the value of inductance L for which the current is maximum in a series LCR circuit with C = 10 $$\mu$$F and $$\omega$$ = 1000 s$$-$$1 ?
A
1 mH
B
cannot be calculated unless R is known
C
10 mH
D
100 mH
4
AIPMT 2007
+4
-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
A
50%
B
90%
C
10%
D
30%
EXAM MAP
Medical
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