DC Circuits Flashcards
The condition in Ohm’s law is that
A. ratio V/I should be constant
B. current should be proportional to voltage
C. the temperature should remain constant
D. the temperature should var
the temperature should remain constant
The curve representing Ohm’s law is
A. parabola
B. Linear
C. sine function
D. a hyperbola
linear
The resistance of a rod does NOT depend on:
A. the shape of cross-sectional area
B. its length
C. its material
D. its temperature
the shape of cross-sectional area
The specific resistance ρ depends upon
A. The area of cross-section and the length of the conductor
B. The material of the conductor, its area of cross-section and length
C. The nature of the material of the conductor only
D. The area of cross-section of the conductor
The nature of the material of the conductor only
A copper wire is drawn down such that its length is doubled but the volume remains the same, what is the new resistance of the wire?
A. R1
B. R1/2
C. 2R1
D. 4R1
4R1
When electrons build up pressure at one point, it is called _______.
A. ganging
B. current flow
C. impedance
D. pressure filling
current flow
Two wires made of the same material have the same lengths but different diameters. They are connected in SERIES to a battery. Which of the following quantity is the same for the two wires?
A. current
B. Current density
C. voltage
D. end-to-end potential difference
Current
The current is zero in a conductor when NO potential difference is applied because
A. the electrons are not moving fast enough
B. equal numbers of electrons and protons are moving together
C. the electrons are not moving
D. for every electron with a given velocity there is another with a velocity of equal magnitude and opposite direction
for every electron with a given velocity there is another with a velocity of equal magnitude and opposite direction
The magnetic potential in a magnetic circuit can be measured in terms of
A. farads
B. M.M.F.
C. coulombs
D. none of these
M.M.F.
The tesla is a unit of _______________.
A. inductance
B. magnetic flux density
C. capacitance
D. permittivity
magnetic flux density
What is the counterpart of magnetic flux in an electric circuit?
A. Voltage
B. Current
C. Resistance
D. Conductance
Current
Whenever a conductor cuts magnetic flux, an emf is induced in that conductor. This statement is due to
A. Joule’s Law
B. Coulomb’s Law
C. Faraday’s Law
D. Weber and Ewing’s theory
Faraday’s Law
The law that induces emf and current alwayas opposes the cause producing them was discovered by
A. Faraday
B. Maxwell
C. Lenz
D. Ohm
Lenz
In the left hand rule, thumb always represents
A. voltage
B. current
C. direction of force on conductor
D. magnetic field
direction of force on conductor
Which of the following is NOT a property of magnetic field lines?
A. The field is stronger where the lines are closer together.
B. The lines intersect surfaces of equal intensity at right angles.
C. Magnetic field lines have no beginnings and no ends.
D. The lines cross themselves only at right angles.
The lines cross themselves only at right angles.
Positive charge is distributed uniformly throughout a non-conducting sphere. The highest electric potential occurs _________.
A. far from the sphere
B. at the center
C. just outside the surface
D. at the surface
at the center
The coulomb force F acts on two charges a distance r, apart. What is F proportional to?
A. R
B. 1/r^2
C. r^2
D. 1/r^3
1/r^2
Current has units of ____________.
A. coulomb
B. ohm
C. coulomb/second
D. volt
coulomb/second
A parallel plate capacitor with plates of area A that are separated a distance d by air is initially charged with charge q. The energy stored in the capacitor initially E. The plates are then separated by 2d. What is the new energy stored in the capacitor?
A. 1/2 E
B. 0
C. 2E
D. E
2E
A voltmeter consists of a meter movement in series with __________.
A. a battery
B. high resistance
C. negligible resistance
D. battery and resistor
high resistance
What extends the range of a dc ammeter?
A. Inductance
B. capacitor
C. current transformer
D. shunt resistance
shunt resistance
Which of the following characteristic of the plates of the battery will the Ampere-Hour of the battery depends on?
A. distance
B. area
C. strength
D. thickness
area
Resistor 1 has twice the resistance of resistor 2. They are connected in parallel to a battery. Find the ratio of the thermal energy generation rate in resistor 1 to that in resistor 2.
A. 2:1
B. 1:4
C. 4:1
D. 1:2
1:2
Transient current in a circuit results from
A. voltage applied to the circuit
B. impedance of the circuit
C. changes in the stored energy in inductors and capacitors
D. resistance of the circuit
changes in the stored energy in inductors and capacitors
The voltage applied across an electric press was reduced by 50%. The power consumed by the press will be reduced to
A. 25%
B. 50%
C. 60%
D. 75%
25%
Two resistors are connected in parallel across a potential difference. The resistance of resistor A is twice that of resistor B. If the current carried by resistor A is I, then what is the current carried by B?
A. 4I
B. 2I
C. I/4
D. I/2
(I as in island)
2I
