# <!--td {border: 1px solid #ccc;}br {mso-data-placement:same-cell;}--> Alternating current cannot be measured by a D.C. ammeter because: 1. A.C. cannot pass through D.C. Ammeter 2. A. C. changes direction 3. Average value of current for the complete cycle is zero 4. D.C. Ammeter will get damaged

Subtopic:  AC vs DC |
64%
Hints

In an L-R circuit, the inductive reactance is equal to the resistance R of the circuit. An emf of E = E0cos(ωt) is applied to the circuit. The power consumed by the circuit is:

1. $\frac{{\mathrm{E}}_{0}^{2}}{\sqrt{2}\mathrm{R}}$

2. $\frac{{\mathrm{E}}_{0}^{2}}{4\mathrm{R}}$

3. $\frac{{\mathrm{E}}_{0}^{2}}{2\mathrm{R}}$

4. $\frac{{\mathrm{E}}_{0}^{2}}{8\mathrm{R}}$

Subtopic:  Power factor |
53%
From NCERT
To view explanation, please take trial in the course.
NEET 2023 - Target Batch - Aryan Raj Singh
Hints
To view explanation, please take trial in the course.
NEET 2023 - Target Batch - Aryan Raj Singh

A series AC circuit has a resistance of 4 $\mathrm{\Omega }$ and an inductor of reactance 3 $\mathrm{\Omega }$. The impedance of the circuit is z1. Now when a capacitor of reactance 6 $\mathrm{\Omega }$ is connected in series with the above combination, the impedance becomes ${z}_{2.}$ $\frac{{\mathrm{z}}_{1}}{{\mathrm{z}}_{2}}$ will be:

1. 1 : 1

2. 5 : 4

3. 4 : 5

4. 2 : 1

Subtopic:  Different Types of AC Circuits |
86%
From NCERT
To view explanation, please take trial in the course.
NEET 2023 - Target Batch - Aryan Raj Singh
Hints
To view explanation, please take trial in the course.
NEET 2023 - Target Batch - Aryan Raj Singh

An inductor (L) and resistance (R) are connected in series with  an AC source. The phase difference between voltage (V) and current (i) is $45°$. If the phase difference between V and i remains the same, then the capacitive reactance and impedance of the L-C-R circuit will be:

1. 2R, R$\sqrt{2}$

2. R, R$\sqrt{2}$

3. R, R

4. 2R, R$\sqrt{3}$

Subtopic:  Different Types of AC Circuits |
54%
From NCERT
To view explanation, please take trial in the course.
NEET 2023 - Target Batch - Aryan Raj Singh
Hints
To view explanation, please take trial in the course.
NEET 2023 - Target Batch - Aryan Raj Singh

What is the value of inductance L for which the current is a maximum in a series LCR circuit with C=10 μF and $\mathrm{\omega }$ = 1000 s-1?

 1 10 mH 2 100 mH 3 1 mH 4 Cannot be calculated unless R is known

Subtopic:  Different Types of AC Circuits |
77%
Hints

A 50 Hz a.c. source of 20 volts is connected across R and C as shown in the figure below. If the voltage across R is 12 volts, then the voltage across C will be:

 1 8 V 2 16 V 3 10 V 4 not possible to determine unless values of R and C are given

Subtopic:  Different Types of AC Circuits |
72%
From NCERT
To view explanation, please take trial in the course.
NEET 2023 - Target Batch - Aryan Raj Singh
Hints
To view explanation, please take trial in the course.
NEET 2023 - Target Batch - Aryan Raj Singh

A transformer has an efficiency of 90% when working on a 200 V and 3 kW power supply. If the current in the secondary coil is 6 A, the voltage across the secondary coil and the current in the primary coil, respectively, are:

1. 300 V, 15 A

2. 450 V, 15 A

3. 450 V, 13.5 A

4. 600 V, 15 A

Subtopic:  Transformer |
74%
From NCERT
AIPMT - 2014
To view explanation, please take trial in the course.
NEET 2023 - Target Batch - Aryan Raj Singh
Hints
To view explanation, please take trial in the course.
NEET 2023 - Target Batch - Aryan Raj Singh

The core of a transformer is laminated because:

 1 Energy losses due to eddy currents may be minimized 2 The weight of the transformer may be reduced 3 Rusting of the core may be prevented 4 Ratio of voltage in primary and secondary may be increased
Subtopic:  Transformer |
90%
From NCERT
AIPMT - 2006
To view explanation, please take trial in the course.
NEET 2023 - Target Batch - Aryan Raj Singh
Hints
To view explanation, please take trial in the course.
NEET 2023 - Target Batch - Aryan Raj Singh

How much power is dissipated in an $$\mathrm{L-C-R}$$ series circuit connected to an $$\mathrm{AC}$$ source of emf $$\mathrm E$$?

 1 $$\frac{\varepsilon^{2} R}{\left[R^{2}+\left(L \omega-\frac{1}{C \omega}\right)^{2}\right]}$$ 2 $$\frac{\varepsilon^{2} \sqrt{R^{2}+\left(L \omega-\frac{1}{C \omega}\right)^{2}}}{R}$$ 3 $$\frac{\varepsilon^{2}\left[R^{2}+\left(L \omega-\frac{1}{C \omega}\right)^{2}\right]}{R}$$ 4 $$\frac{\varepsilon^{2}R}{\sqrt{R^{2}+\left(L \omega-\frac{1}{C \omega}\right)^{2}}}$$
Subtopic:  Power factor |
71%
From NCERT
AIPMT - 2009
To view explanation, please take trial in the course.
NEET 2023 - Target Batch - Aryan Raj Singh
Hints
To view explanation, please take trial in the course.
NEET 2023 - Target Batch - Aryan Raj Singh

A coil of inductive reactance of 31 Ω has a resistance of 8 Ω. It is placed in series with a condenser of capacitive reactance 25 Ω. The combination is connected to an a.c. source of 110 V. The power factor of the circuit is:

1. 0.56

2. 0.64

3. 0.80

4. 0.33

Subtopic:  Power factor |
84%
From NCERT
AIPMT - 2006
To view explanation, please take trial in the course.
NEET 2023 - Target Batch - Aryan Raj Singh
Hints