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Electric Circuits
The electric potential difference between two points A and B is 42 V. What is the work done by an external agent in carrying a charge of
50×10−5C
from A to B at constant speed?
50×10−5C
from A to B at constant speed?
Electric Circuits
An electrical source with internal resistance r is used to operate a lamp of resistance R. What fraction of the total power is delivered to the lamp?
R+rR
R−rR
RR+r
Rr
R+rR
R−rR
RR+r
Rr
Electric Circuits
What is the function of the quartz crystal used in a digital watch?
Electric Circuits
For a metallic conductor, Ohm's law holds provided
potential difference varies
current remains constant
temperature remains constant
potential difference remains constant
potential difference varies
current remains constant
temperature remains constant
potential difference remains constant
Electric Circuits
In an experiment, potential difference is plotted on the vertical axis and current on the horizontal axis. The slope of the graph represents
resistivity
conductivity
resistance
conductance
resistivity
conductivity
resistance
conductance
Electric Circuits
Which of the following is NOT true about a rheostat?
It is a constant current instrument
It is a resistor with moving contact
It is used for varying the current in a circuit
It is used for varying the resistance in a circuit
It is a constant current instrument
It is a resistor with moving contact
It is used for varying the current in a circuit
It is used for varying the resistance in a circuit
Electric Circuits
The potentiometer wire plays equivalent role of which of these devices in a circuit?
rheostat
thermostat
galvanometer
ammeter
rheostat
thermostat
galvanometer
ammeter
Electric Circuits
From Gauss’ law which of the following is NOT correct?
The outward flux of electric field through an enclosed surface is proportional to the electric charges enclosed
The field at a point outside a spherically symmetric charge is the same as the electric field at the same point due to a point charge at its centre.
The electric flux through a Gaussian surface is a vector product of the electric field and a unit vector perpendicular to and outward from the surface
The total electric flux through a cylinder placed in an electric field with its axis parallel to the field is zero
The outward flux of electric field through an enclosed surface is proportional to the electric charges enclosed
The field at a point outside a spherically symmetric charge is the same as the electric field at the same point due to a point charge at its centre.
The electric flux through a Gaussian surface is a vector product of the electric field and a unit vector perpendicular to and outward from the surface
The total electric flux through a cylinder placed in an electric field with its axis parallel to the field is zero
Electric Circuits
The following are true about electric field lines except that they
a. are drawn such that the magnitude of the field is proportional to the number of lines crossing a unit area perpendicular to the lines
b. not intersect one another
c. are discontinuous and may terminate in a vacuum
d. give the direction of motion of a unit positive test-charge under the action of the electrostatic force
a. are drawn such that the magnitude of the field is proportional to the number of lines crossing a unit area perpendicular to the lines
b. not intersect one another
c. are discontinuous and may terminate in a vacuum
d. give the direction of motion of a unit positive test-charge under the action of the electrostatic force
Electric Circuits
When electric charges move in closed loops ------- force is produced
a) electrostatic
b) magnetic
c) gravitational
d) nuclear
a) electrostatic
b) magnetic
c) gravitational
d) nuclear
