274665
A.C. power is transmitted from a power house at a high voltage as
1 the rate of transmission is faster at high voltages
2 it is more economical due to less power loss
3 power cannot be transmitted at low voltages
4 a precaution against theft of transmission lines
Explanation:
(b)
NCERT Page-252 / N-191
AC (NCERT)
274666
An alternating voltage $\text{V}={{\text{V}}_{0}}\text{sin}\omega \text{t}$ is applied across a circuit. As a result, a current $I={{I}_{0}}\text{sin}\left( \omega t-\pi /2 \right)$ flows in it. The power consumed per cycle is
1 zero
2 $0.5{{\text{V}}_{0}}{{\text{I}}_{0}}$
3 $0.707{{\text{V}}_{0}}{{\text{I}}_{0}}$
4 $1.414{{\text{V}}_{0}}{{\text{I}}_{0}}$
Explanation:
(a) The phase angle between voltage $V$. and current $I$ is $\pi /2$. Therefore, power factor $\text{cos}\phi =\text{cos}\left( \pi /2 \right)=0$. Hence the power consumed is zero.
NCERT Page-252 / N-191
AC (NCERT)
274667
The heat produced in a given resistance in a given time by the sinusoidal current ${{I}_{0}}\text{sin}\omega t$ will be the same as that of a steady current of magnitude nearly
1 $0.71{{\text{I}}_{0}}$
2 $1.412{{\text{I}}_{0}}$
3 ${{\text{I}}_{0}}$
4 $\sqrt{{{I}_{0}}}$
Explanation:
(a)
NCERT Page-252/ N-191
AC (NCERT)
274668
An alternating e.m.f. of angular frequency $\omega $ is applied across an inductance. The instantaneous power developed in the circuit has an angular frequency
1 $\frac{\omega }{4}$
2 $\frac{\omega }{2}$
3 $\omega $
4 $2\omega $
Explanation:
(d) Instantaneous values of emf and current in inductive circuit are given by $E={{E}_{0}}\text{sin}\omega t$ and $i={{i}_{0}}\text{sin}\left( \omega t-\frac{\pi }{2} \right)$ respectively.
$\therefore {{\text{P}}_{\text{inst }\!\!~\!\!\text{ }}}=E.i={{E}_{0}}\text{Sin}\omega \text{t}\times {{i}_{0}}\text{Sin}\left( \omega \text{t}-\frac{\pi }{2} \right)$
$={{E}_{0}}{{i}_{0}}\text{sin}\omega t\left( \text{sin}\omega t\text{cos}\frac{\pi }{2}-\text{cos}\omega t\text{sin}\frac{\pi }{2} \right)$
$=-{{E}_{0}}{{i}_{0}}\text{sin}\omega t\text{cos}\omega t$
$=-\frac{1}{2}{{E}_{0}}{{i}_{0}}\text{sin}2\omega t\left( \text{sin}2\omega \text{t}=2\text{sin}\omega \text{tcos}\omega \text{t} \right)$
Hence, angular frequency of instantaneous power is $2\omega $
274665
A.C. power is transmitted from a power house at a high voltage as
1 the rate of transmission is faster at high voltages
2 it is more economical due to less power loss
3 power cannot be transmitted at low voltages
4 a precaution against theft of transmission lines
Explanation:
(b)
NCERT Page-252 / N-191
AC (NCERT)
274666
An alternating voltage $\text{V}={{\text{V}}_{0}}\text{sin}\omega \text{t}$ is applied across a circuit. As a result, a current $I={{I}_{0}}\text{sin}\left( \omega t-\pi /2 \right)$ flows in it. The power consumed per cycle is
1 zero
2 $0.5{{\text{V}}_{0}}{{\text{I}}_{0}}$
3 $0.707{{\text{V}}_{0}}{{\text{I}}_{0}}$
4 $1.414{{\text{V}}_{0}}{{\text{I}}_{0}}$
Explanation:
(a) The phase angle between voltage $V$. and current $I$ is $\pi /2$. Therefore, power factor $\text{cos}\phi =\text{cos}\left( \pi /2 \right)=0$. Hence the power consumed is zero.
NCERT Page-252 / N-191
AC (NCERT)
274667
The heat produced in a given resistance in a given time by the sinusoidal current ${{I}_{0}}\text{sin}\omega t$ will be the same as that of a steady current of magnitude nearly
1 $0.71{{\text{I}}_{0}}$
2 $1.412{{\text{I}}_{0}}$
3 ${{\text{I}}_{0}}$
4 $\sqrt{{{I}_{0}}}$
Explanation:
(a)
NCERT Page-252/ N-191
AC (NCERT)
274668
An alternating e.m.f. of angular frequency $\omega $ is applied across an inductance. The instantaneous power developed in the circuit has an angular frequency
1 $\frac{\omega }{4}$
2 $\frac{\omega }{2}$
3 $\omega $
4 $2\omega $
Explanation:
(d) Instantaneous values of emf and current in inductive circuit are given by $E={{E}_{0}}\text{sin}\omega t$ and $i={{i}_{0}}\text{sin}\left( \omega t-\frac{\pi }{2} \right)$ respectively.
$\therefore {{\text{P}}_{\text{inst }\!\!~\!\!\text{ }}}=E.i={{E}_{0}}\text{Sin}\omega \text{t}\times {{i}_{0}}\text{Sin}\left( \omega \text{t}-\frac{\pi }{2} \right)$
$={{E}_{0}}{{i}_{0}}\text{sin}\omega t\left( \text{sin}\omega t\text{cos}\frac{\pi }{2}-\text{cos}\omega t\text{sin}\frac{\pi }{2} \right)$
$=-{{E}_{0}}{{i}_{0}}\text{sin}\omega t\text{cos}\omega t$
$=-\frac{1}{2}{{E}_{0}}{{i}_{0}}\text{sin}2\omega t\left( \text{sin}2\omega \text{t}=2\text{sin}\omega \text{tcos}\omega \text{t} \right)$
Hence, angular frequency of instantaneous power is $2\omega $
274665
A.C. power is transmitted from a power house at a high voltage as
1 the rate of transmission is faster at high voltages
2 it is more economical due to less power loss
3 power cannot be transmitted at low voltages
4 a precaution against theft of transmission lines
Explanation:
(b)
NCERT Page-252 / N-191
AC (NCERT)
274666
An alternating voltage $\text{V}={{\text{V}}_{0}}\text{sin}\omega \text{t}$ is applied across a circuit. As a result, a current $I={{I}_{0}}\text{sin}\left( \omega t-\pi /2 \right)$ flows in it. The power consumed per cycle is
1 zero
2 $0.5{{\text{V}}_{0}}{{\text{I}}_{0}}$
3 $0.707{{\text{V}}_{0}}{{\text{I}}_{0}}$
4 $1.414{{\text{V}}_{0}}{{\text{I}}_{0}}$
Explanation:
(a) The phase angle between voltage $V$. and current $I$ is $\pi /2$. Therefore, power factor $\text{cos}\phi =\text{cos}\left( \pi /2 \right)=0$. Hence the power consumed is zero.
NCERT Page-252 / N-191
AC (NCERT)
274667
The heat produced in a given resistance in a given time by the sinusoidal current ${{I}_{0}}\text{sin}\omega t$ will be the same as that of a steady current of magnitude nearly
1 $0.71{{\text{I}}_{0}}$
2 $1.412{{\text{I}}_{0}}$
3 ${{\text{I}}_{0}}$
4 $\sqrt{{{I}_{0}}}$
Explanation:
(a)
NCERT Page-252/ N-191
AC (NCERT)
274668
An alternating e.m.f. of angular frequency $\omega $ is applied across an inductance. The instantaneous power developed in the circuit has an angular frequency
1 $\frac{\omega }{4}$
2 $\frac{\omega }{2}$
3 $\omega $
4 $2\omega $
Explanation:
(d) Instantaneous values of emf and current in inductive circuit are given by $E={{E}_{0}}\text{sin}\omega t$ and $i={{i}_{0}}\text{sin}\left( \omega t-\frac{\pi }{2} \right)$ respectively.
$\therefore {{\text{P}}_{\text{inst }\!\!~\!\!\text{ }}}=E.i={{E}_{0}}\text{Sin}\omega \text{t}\times {{i}_{0}}\text{Sin}\left( \omega \text{t}-\frac{\pi }{2} \right)$
$={{E}_{0}}{{i}_{0}}\text{sin}\omega t\left( \text{sin}\omega t\text{cos}\frac{\pi }{2}-\text{cos}\omega t\text{sin}\frac{\pi }{2} \right)$
$=-{{E}_{0}}{{i}_{0}}\text{sin}\omega t\text{cos}\omega t$
$=-\frac{1}{2}{{E}_{0}}{{i}_{0}}\text{sin}2\omega t\left( \text{sin}2\omega \text{t}=2\text{sin}\omega \text{tcos}\omega \text{t} \right)$
Hence, angular frequency of instantaneous power is $2\omega $
274665
A.C. power is transmitted from a power house at a high voltage as
1 the rate of transmission is faster at high voltages
2 it is more economical due to less power loss
3 power cannot be transmitted at low voltages
4 a precaution against theft of transmission lines
Explanation:
(b)
NCERT Page-252 / N-191
AC (NCERT)
274666
An alternating voltage $\text{V}={{\text{V}}_{0}}\text{sin}\omega \text{t}$ is applied across a circuit. As a result, a current $I={{I}_{0}}\text{sin}\left( \omega t-\pi /2 \right)$ flows in it. The power consumed per cycle is
1 zero
2 $0.5{{\text{V}}_{0}}{{\text{I}}_{0}}$
3 $0.707{{\text{V}}_{0}}{{\text{I}}_{0}}$
4 $1.414{{\text{V}}_{0}}{{\text{I}}_{0}}$
Explanation:
(a) The phase angle between voltage $V$. and current $I$ is $\pi /2$. Therefore, power factor $\text{cos}\phi =\text{cos}\left( \pi /2 \right)=0$. Hence the power consumed is zero.
NCERT Page-252 / N-191
AC (NCERT)
274667
The heat produced in a given resistance in a given time by the sinusoidal current ${{I}_{0}}\text{sin}\omega t$ will be the same as that of a steady current of magnitude nearly
1 $0.71{{\text{I}}_{0}}$
2 $1.412{{\text{I}}_{0}}$
3 ${{\text{I}}_{0}}$
4 $\sqrt{{{I}_{0}}}$
Explanation:
(a)
NCERT Page-252/ N-191
AC (NCERT)
274668
An alternating e.m.f. of angular frequency $\omega $ is applied across an inductance. The instantaneous power developed in the circuit has an angular frequency
1 $\frac{\omega }{4}$
2 $\frac{\omega }{2}$
3 $\omega $
4 $2\omega $
Explanation:
(d) Instantaneous values of emf and current in inductive circuit are given by $E={{E}_{0}}\text{sin}\omega t$ and $i={{i}_{0}}\text{sin}\left( \omega t-\frac{\pi }{2} \right)$ respectively.
$\therefore {{\text{P}}_{\text{inst }\!\!~\!\!\text{ }}}=E.i={{E}_{0}}\text{Sin}\omega \text{t}\times {{i}_{0}}\text{Sin}\left( \omega \text{t}-\frac{\pi }{2} \right)$
$={{E}_{0}}{{i}_{0}}\text{sin}\omega t\left( \text{sin}\omega t\text{cos}\frac{\pi }{2}-\text{cos}\omega t\text{sin}\frac{\pi }{2} \right)$
$=-{{E}_{0}}{{i}_{0}}\text{sin}\omega t\text{cos}\omega t$
$=-\frac{1}{2}{{E}_{0}}{{i}_{0}}\text{sin}2\omega t\left( \text{sin}2\omega \text{t}=2\text{sin}\omega \text{tcos}\omega \text{t} \right)$
Hence, angular frequency of instantaneous power is $2\omega $
