155003
A generator produces a voltage that is given by $V=240 \sin 120 t$ where $t$ is in sec. The frequency and rms voltage are
1 $19 \mathrm{~Hz}$ and $170 \mathrm{~V}$
2 $19 \mathrm{~Hz}$ and $120 \mathrm{~V}$
3 $60 \mathrm{~Hz}$ and $240 \mathrm{~V}$
4 $754 \mathrm{~Hz}$ and $70 \mathrm{~V}$
Explanation:
A Given, Voltage, $\mathrm{V}=240 \sin 120 \mathrm{t}$ Standard equation, $\mathrm{V}=\mathrm{V}_{0} \sin \omega \mathrm{t}$ From equation (i) \& (ii), we get- $\mathrm{V}_{0}=240 \mathrm{~V}$ $\omega=120 \mathrm{rad} / \mathrm{sec}$ rms value of voltage, $\mathrm{V}_{\mathrm{rms}}=\frac{\mathrm{V}_{0}}{\sqrt{2}}=\frac{240}{\sqrt{2}}=170 \mathrm{~V}$ Now, frequency- $\omega=2 \pi f$ $f=\frac{\omega}{2 \pi}=\frac{120}{2 \times 3.14}=19 \mathrm{~Hz}$
COMEDK 2016
Alternating Current
155004
Assertion: The resistance offered by an inductor in a d.c. circuit is always constant. Reason: The resistance of inductor in steady state is non-zero.
1 If both Assertion and Reason are correct and reason is the correct explanation of the Assertion.
2 If both Assertion and Reason are correct, but the Reason is not the correct explanation of the Assertion
3 If Assertion is correct but Reason is incorrect
4 If both the Assertion and Reason are incorrect
Explanation:
D Resistance offered by an inductor in a d.c. circuit at $\mathrm{t}=0$ is infinity, which decreases to zero at steady current. Hence, both the assertion and reason incorrect.
AIIMS-2010
Alternating Current
155005
Assertion: Long distance power transmission is done at high voltage. Reason: At high voltage supply power losses are less.
1 If both Assertion and Reason are correct and reason is the correct explanation of Assertion.
2 If both Assertion and Reason are correct, but Reason is not the correct explanation of Assertion
3 If Assertion is correct but Reason is incorrect
4 If both the Assertion and Reason are incorrect
Explanation:
A At long distance power transmission is done at high voltage. Power loss $=\mathrm{I}^{2} \mathrm{R}=\left(\frac{\mathrm{P}}{\mathrm{V}}\right)^{2} \mathrm{R}$ Where, $\mathrm{P}=$ Transmitted power At high voltage power losses are less. Hence, both (A) and (R) are correct and (R) is the correct explanation of (A).
AIIMS-2011
Alternating Current
155006
An AC source is $120 \mathrm{~V}-60 \mathrm{~Hz}$. The value of voltage after $\frac{1}{720} \mathrm{~s}$ from start will be-
1 $20.2 \mathrm{~V}$
2 $42.4 \mathrm{~V}$
3 $84.8 \mathrm{~V}$
4 $106.8 \mathrm{~V}$
Explanation:
C Given, $\mathrm{V}_{\mathrm{rms}}=120 \mathrm{~V}$ Frequency, $\mathrm{f}=60 \mathrm{~Hz}$ Time, $\mathrm{t}=\frac{1}{720} \mathrm{sec}$ Standard equation of AC voltage, $\mathrm{V}=\mathrm{V}_{0} \sin \omega \mathrm{t}$ Where, $\mathrm{V}_{0}=\sqrt{2} \mathrm{~V}_{\mathrm{rms}}=\sqrt{2} \times 120=120 \sqrt{2} \mathrm{~V}$ Put the value in eq ${ }^{\mathrm{n}}(\mathrm{i})-$ $\mathrm{V} =120 \sqrt{2} \times \sin (2 \pi \mathrm{ft}) \quad[\omega=2 \pi \mathrm{f}]$ $=120 \sqrt{2} \sin \left(2 \times \pi \times 60 \times \frac{1}{720}\right)$ $=60 \sqrt{2}=84.8 \mathrm{~V}$
155003
A generator produces a voltage that is given by $V=240 \sin 120 t$ where $t$ is in sec. The frequency and rms voltage are
1 $19 \mathrm{~Hz}$ and $170 \mathrm{~V}$
2 $19 \mathrm{~Hz}$ and $120 \mathrm{~V}$
3 $60 \mathrm{~Hz}$ and $240 \mathrm{~V}$
4 $754 \mathrm{~Hz}$ and $70 \mathrm{~V}$
Explanation:
A Given, Voltage, $\mathrm{V}=240 \sin 120 \mathrm{t}$ Standard equation, $\mathrm{V}=\mathrm{V}_{0} \sin \omega \mathrm{t}$ From equation (i) \& (ii), we get- $\mathrm{V}_{0}=240 \mathrm{~V}$ $\omega=120 \mathrm{rad} / \mathrm{sec}$ rms value of voltage, $\mathrm{V}_{\mathrm{rms}}=\frac{\mathrm{V}_{0}}{\sqrt{2}}=\frac{240}{\sqrt{2}}=170 \mathrm{~V}$ Now, frequency- $\omega=2 \pi f$ $f=\frac{\omega}{2 \pi}=\frac{120}{2 \times 3.14}=19 \mathrm{~Hz}$
COMEDK 2016
Alternating Current
155004
Assertion: The resistance offered by an inductor in a d.c. circuit is always constant. Reason: The resistance of inductor in steady state is non-zero.
1 If both Assertion and Reason are correct and reason is the correct explanation of the Assertion.
2 If both Assertion and Reason are correct, but the Reason is not the correct explanation of the Assertion
3 If Assertion is correct but Reason is incorrect
4 If both the Assertion and Reason are incorrect
Explanation:
D Resistance offered by an inductor in a d.c. circuit at $\mathrm{t}=0$ is infinity, which decreases to zero at steady current. Hence, both the assertion and reason incorrect.
AIIMS-2010
Alternating Current
155005
Assertion: Long distance power transmission is done at high voltage. Reason: At high voltage supply power losses are less.
1 If both Assertion and Reason are correct and reason is the correct explanation of Assertion.
2 If both Assertion and Reason are correct, but Reason is not the correct explanation of Assertion
3 If Assertion is correct but Reason is incorrect
4 If both the Assertion and Reason are incorrect
Explanation:
A At long distance power transmission is done at high voltage. Power loss $=\mathrm{I}^{2} \mathrm{R}=\left(\frac{\mathrm{P}}{\mathrm{V}}\right)^{2} \mathrm{R}$ Where, $\mathrm{P}=$ Transmitted power At high voltage power losses are less. Hence, both (A) and (R) are correct and (R) is the correct explanation of (A).
AIIMS-2011
Alternating Current
155006
An AC source is $120 \mathrm{~V}-60 \mathrm{~Hz}$. The value of voltage after $\frac{1}{720} \mathrm{~s}$ from start will be-
1 $20.2 \mathrm{~V}$
2 $42.4 \mathrm{~V}$
3 $84.8 \mathrm{~V}$
4 $106.8 \mathrm{~V}$
Explanation:
C Given, $\mathrm{V}_{\mathrm{rms}}=120 \mathrm{~V}$ Frequency, $\mathrm{f}=60 \mathrm{~Hz}$ Time, $\mathrm{t}=\frac{1}{720} \mathrm{sec}$ Standard equation of AC voltage, $\mathrm{V}=\mathrm{V}_{0} \sin \omega \mathrm{t}$ Where, $\mathrm{V}_{0}=\sqrt{2} \mathrm{~V}_{\mathrm{rms}}=\sqrt{2} \times 120=120 \sqrt{2} \mathrm{~V}$ Put the value in eq ${ }^{\mathrm{n}}(\mathrm{i})-$ $\mathrm{V} =120 \sqrt{2} \times \sin (2 \pi \mathrm{ft}) \quad[\omega=2 \pi \mathrm{f}]$ $=120 \sqrt{2} \sin \left(2 \times \pi \times 60 \times \frac{1}{720}\right)$ $=60 \sqrt{2}=84.8 \mathrm{~V}$
155003
A generator produces a voltage that is given by $V=240 \sin 120 t$ where $t$ is in sec. The frequency and rms voltage are
1 $19 \mathrm{~Hz}$ and $170 \mathrm{~V}$
2 $19 \mathrm{~Hz}$ and $120 \mathrm{~V}$
3 $60 \mathrm{~Hz}$ and $240 \mathrm{~V}$
4 $754 \mathrm{~Hz}$ and $70 \mathrm{~V}$
Explanation:
A Given, Voltage, $\mathrm{V}=240 \sin 120 \mathrm{t}$ Standard equation, $\mathrm{V}=\mathrm{V}_{0} \sin \omega \mathrm{t}$ From equation (i) \& (ii), we get- $\mathrm{V}_{0}=240 \mathrm{~V}$ $\omega=120 \mathrm{rad} / \mathrm{sec}$ rms value of voltage, $\mathrm{V}_{\mathrm{rms}}=\frac{\mathrm{V}_{0}}{\sqrt{2}}=\frac{240}{\sqrt{2}}=170 \mathrm{~V}$ Now, frequency- $\omega=2 \pi f$ $f=\frac{\omega}{2 \pi}=\frac{120}{2 \times 3.14}=19 \mathrm{~Hz}$
COMEDK 2016
Alternating Current
155004
Assertion: The resistance offered by an inductor in a d.c. circuit is always constant. Reason: The resistance of inductor in steady state is non-zero.
1 If both Assertion and Reason are correct and reason is the correct explanation of the Assertion.
2 If both Assertion and Reason are correct, but the Reason is not the correct explanation of the Assertion
3 If Assertion is correct but Reason is incorrect
4 If both the Assertion and Reason are incorrect
Explanation:
D Resistance offered by an inductor in a d.c. circuit at $\mathrm{t}=0$ is infinity, which decreases to zero at steady current. Hence, both the assertion and reason incorrect.
AIIMS-2010
Alternating Current
155005
Assertion: Long distance power transmission is done at high voltage. Reason: At high voltage supply power losses are less.
1 If both Assertion and Reason are correct and reason is the correct explanation of Assertion.
2 If both Assertion and Reason are correct, but Reason is not the correct explanation of Assertion
3 If Assertion is correct but Reason is incorrect
4 If both the Assertion and Reason are incorrect
Explanation:
A At long distance power transmission is done at high voltage. Power loss $=\mathrm{I}^{2} \mathrm{R}=\left(\frac{\mathrm{P}}{\mathrm{V}}\right)^{2} \mathrm{R}$ Where, $\mathrm{P}=$ Transmitted power At high voltage power losses are less. Hence, both (A) and (R) are correct and (R) is the correct explanation of (A).
AIIMS-2011
Alternating Current
155006
An AC source is $120 \mathrm{~V}-60 \mathrm{~Hz}$. The value of voltage after $\frac{1}{720} \mathrm{~s}$ from start will be-
1 $20.2 \mathrm{~V}$
2 $42.4 \mathrm{~V}$
3 $84.8 \mathrm{~V}$
4 $106.8 \mathrm{~V}$
Explanation:
C Given, $\mathrm{V}_{\mathrm{rms}}=120 \mathrm{~V}$ Frequency, $\mathrm{f}=60 \mathrm{~Hz}$ Time, $\mathrm{t}=\frac{1}{720} \mathrm{sec}$ Standard equation of AC voltage, $\mathrm{V}=\mathrm{V}_{0} \sin \omega \mathrm{t}$ Where, $\mathrm{V}_{0}=\sqrt{2} \mathrm{~V}_{\mathrm{rms}}=\sqrt{2} \times 120=120 \sqrt{2} \mathrm{~V}$ Put the value in eq ${ }^{\mathrm{n}}(\mathrm{i})-$ $\mathrm{V} =120 \sqrt{2} \times \sin (2 \pi \mathrm{ft}) \quad[\omega=2 \pi \mathrm{f}]$ $=120 \sqrt{2} \sin \left(2 \times \pi \times 60 \times \frac{1}{720}\right)$ $=60 \sqrt{2}=84.8 \mathrm{~V}$
155003
A generator produces a voltage that is given by $V=240 \sin 120 t$ where $t$ is in sec. The frequency and rms voltage are
1 $19 \mathrm{~Hz}$ and $170 \mathrm{~V}$
2 $19 \mathrm{~Hz}$ and $120 \mathrm{~V}$
3 $60 \mathrm{~Hz}$ and $240 \mathrm{~V}$
4 $754 \mathrm{~Hz}$ and $70 \mathrm{~V}$
Explanation:
A Given, Voltage, $\mathrm{V}=240 \sin 120 \mathrm{t}$ Standard equation, $\mathrm{V}=\mathrm{V}_{0} \sin \omega \mathrm{t}$ From equation (i) \& (ii), we get- $\mathrm{V}_{0}=240 \mathrm{~V}$ $\omega=120 \mathrm{rad} / \mathrm{sec}$ rms value of voltage, $\mathrm{V}_{\mathrm{rms}}=\frac{\mathrm{V}_{0}}{\sqrt{2}}=\frac{240}{\sqrt{2}}=170 \mathrm{~V}$ Now, frequency- $\omega=2 \pi f$ $f=\frac{\omega}{2 \pi}=\frac{120}{2 \times 3.14}=19 \mathrm{~Hz}$
COMEDK 2016
Alternating Current
155004
Assertion: The resistance offered by an inductor in a d.c. circuit is always constant. Reason: The resistance of inductor in steady state is non-zero.
1 If both Assertion and Reason are correct and reason is the correct explanation of the Assertion.
2 If both Assertion and Reason are correct, but the Reason is not the correct explanation of the Assertion
3 If Assertion is correct but Reason is incorrect
4 If both the Assertion and Reason are incorrect
Explanation:
D Resistance offered by an inductor in a d.c. circuit at $\mathrm{t}=0$ is infinity, which decreases to zero at steady current. Hence, both the assertion and reason incorrect.
AIIMS-2010
Alternating Current
155005
Assertion: Long distance power transmission is done at high voltage. Reason: At high voltage supply power losses are less.
1 If both Assertion and Reason are correct and reason is the correct explanation of Assertion.
2 If both Assertion and Reason are correct, but Reason is not the correct explanation of Assertion
3 If Assertion is correct but Reason is incorrect
4 If both the Assertion and Reason are incorrect
Explanation:
A At long distance power transmission is done at high voltage. Power loss $=\mathrm{I}^{2} \mathrm{R}=\left(\frac{\mathrm{P}}{\mathrm{V}}\right)^{2} \mathrm{R}$ Where, $\mathrm{P}=$ Transmitted power At high voltage power losses are less. Hence, both (A) and (R) are correct and (R) is the correct explanation of (A).
AIIMS-2011
Alternating Current
155006
An AC source is $120 \mathrm{~V}-60 \mathrm{~Hz}$. The value of voltage after $\frac{1}{720} \mathrm{~s}$ from start will be-
1 $20.2 \mathrm{~V}$
2 $42.4 \mathrm{~V}$
3 $84.8 \mathrm{~V}$
4 $106.8 \mathrm{~V}$
Explanation:
C Given, $\mathrm{V}_{\mathrm{rms}}=120 \mathrm{~V}$ Frequency, $\mathrm{f}=60 \mathrm{~Hz}$ Time, $\mathrm{t}=\frac{1}{720} \mathrm{sec}$ Standard equation of AC voltage, $\mathrm{V}=\mathrm{V}_{0} \sin \omega \mathrm{t}$ Where, $\mathrm{V}_{0}=\sqrt{2} \mathrm{~V}_{\mathrm{rms}}=\sqrt{2} \times 120=120 \sqrt{2} \mathrm{~V}$ Put the value in eq ${ }^{\mathrm{n}}(\mathrm{i})-$ $\mathrm{V} =120 \sqrt{2} \times \sin (2 \pi \mathrm{ft}) \quad[\omega=2 \pi \mathrm{f}]$ $=120 \sqrt{2} \sin \left(2 \times \pi \times 60 \times \frac{1}{720}\right)$ $=60 \sqrt{2}=84.8 \mathrm{~V}$
