Transcript quiz 13 104 phy in class

Two parallel metal plates carry opposite electrical charges each with
a magnitude of Q. The plates are separated by a distance d and each
plate has an area A.
Consider the following:
I. increasing Q
II. increasing d
III. increasing A
Which of the following would have the effect of reducing the
potential difference between the plates?
(A) I only
(B) II only
(C) III only
(D) I and III
(E) II
and I
A 5x10–6 coulomb electric charge is placed midway between two
parallel metal plates connected to a 9 volt battery. If the electric
charge experiences a force of 1.5 × 10–4 Newtons, what is the
separation
of the metal plates?
(A)6.75x10–9 m
(B)2.7x10–4 m
(C)3.7x10–3m
(D)0.30 m
(E) 3.3 m
All of the following wires are made of the same material but are different
sizes. Identify the wire with the lowest resistance.
If N charge carriers, each of charge q, pass a point in a time t,
then the current in the circuit is
.
Nq
qt
N q t.
t
N
q
t
Consider a wire of resistance R. If it is stretched until it is twice its
original length, while keeping the same volume, its new resistance
will be
A.
R/2
B. R
C. 2R
D. 4R
The resistivity of any given metal
A) depends on its temperature.
B) varies nearly linearly with temperature.
C) is the proportionality constant between the resistance ,R, and
the ratio of the length ,L, to the cross-sectional area ,A, of a wire
made of the metal.
D) has units of ohm-meter.
E) is described by all of the above.
Ans: E
The current in a wire varies with time according to
the relation
I= 4 + 3t2
The number of coulombs of charge that pass a cross section of
the wire between t = 3 s and t = 5 s is
A) 12
B) 48
Ans: D
C) 52
D) 106
E) 305
at 3S
I  4  3  3  4  27  31A
at 5S
I  4  3  52  4  75  79 A
2
Q  It  79  31  2  48  2  96C
If a 12 V battery delivers 100 J in 5 s, find
a)The amount of charge delivered
b)The current produced
The diagram below shows a segment of a circuit. What is the current
in the 200 resistor?
A. 0.5 A
B. 1.0 A
C. 1.5 A
D. 2.0 A
E.There is not enough information to decide.