Physics 121 Multiple Choice Questions
With Solved Solutions.
1. Two point charges, Q1 and Q2 are separated by a distance R. If the magnitudes of BOTH
charges are Doubled and their separation is doubled, what happens to the electrical force that
each charge exerts on the other one?
A) increases by factor of 2
B) increases by factor of sqrt(2)
C) decreases by factor of sqrt(2)
D) increases by factor of 4
E) remains the same - Answer E
F = Q1Q2/r^2
2. What is the direction of the electric field at the position of the X?
A) 1
B) 2
C) 3
D) 4
E) 5 - Answer B
3. The figure shows two unequal charges +q and -Q has greater magnitude than charge +q.
Point X is midway between the charges. In what section of the line will there be a point where
the resultant electric field is zero?
A) VW
B) WX
C) XY
D) YZ - Answer A
, A) a+x
B) x-a
C) x
D) a - Answer A
lambda = Q/L
Dq = lambda dx = Q/L dx R=x-(-a)=x+a
De = - k Q/L (1 / (a+x)^2) dx
5. Points p and q are connected to a battery of fixed voltage. As more resistors R are added to
the parallel circuit, what happens to the total current in the circuit?
A) increases
B) remains the same
C) decreases
D) drops to zero - Answer A
6. Consider the shown. Which of the following statements best describes the current flowing in
the wire connecting points a and b
A) positive current flows from a to b
B) positive current flows from b to a
C) no current flows between a and b
D) none of the above - Answer B
7. In the figure, two identical charges are located at the vertices of an equilateral triangle. The
work required to bring another identical charge from infinity to the other vertex (marked by X)
is
What is the factor?
With Solved Solutions.
1. Two point charges, Q1 and Q2 are separated by a distance R. If the magnitudes of BOTH
charges are Doubled and their separation is doubled, what happens to the electrical force that
each charge exerts on the other one?
A) increases by factor of 2
B) increases by factor of sqrt(2)
C) decreases by factor of sqrt(2)
D) increases by factor of 4
E) remains the same - Answer E
F = Q1Q2/r^2
2. What is the direction of the electric field at the position of the X?
A) 1
B) 2
C) 3
D) 4
E) 5 - Answer B
3. The figure shows two unequal charges +q and -Q has greater magnitude than charge +q.
Point X is midway between the charges. In what section of the line will there be a point where
the resultant electric field is zero?
A) VW
B) WX
C) XY
D) YZ - Answer A
, A) a+x
B) x-a
C) x
D) a - Answer A
lambda = Q/L
Dq = lambda dx = Q/L dx R=x-(-a)=x+a
De = - k Q/L (1 / (a+x)^2) dx
5. Points p and q are connected to a battery of fixed voltage. As more resistors R are added to
the parallel circuit, what happens to the total current in the circuit?
A) increases
B) remains the same
C) decreases
D) drops to zero - Answer A
6. Consider the shown. Which of the following statements best describes the current flowing in
the wire connecting points a and b
A) positive current flows from a to b
B) positive current flows from b to a
C) no current flows between a and b
D) none of the above - Answer B
7. In the figure, two identical charges are located at the vertices of an equilateral triangle. The
work required to bring another identical charge from infinity to the other vertex (marked by X)
is
What is the factor?
