Chapter 21: Electric Currents and Direct-Current Circuits
MCAT Study Guide



1.  

The following information pertains to questions 1 and 2.

The current through a device is measured as a function of the potential difference across the device for several different devices. The results are plotted in the figure at the right.

The Ohmic device which has the largest resistance is represented by the curve labeled ___.
A
B
C
D
E
F

2.  

The Ohmic device which has the smallest resistance is represented by the curve labeled ___.
B
C
D
E
F
G

3.  

The following information pertains to questions 3 and 4.

A variable resistor is wired in series with an ammeter and a battery as in the figure at the right.

If the resistance of the resistor was increased slightly, the current in the circuit as indicated by the ammeter would ___.
increase
decrease
remain constant
be impossible to predict

4.  

If the resistance of the resistor was increased slightly, the rate at which work would be done on the resistor by the battery would ___.
increase
decrease
remain constant
be impossible to predict

5.  

The following information pertains to questions 5-10.

The resistance of seven different resistors is measured as a function of the temperature of the resistors. The results are plotted at the right.

The temperature coefficient of resistance of the resistor represented by the curve labeled C, i. e., alpha.gif (C) is ___ alpha.gif(D).
more than
equal to
less than
incomparable with

6.  

Of the seven resistors, the one for which the magnitude of the temperature coefficient of resistance is smallest is represented by the curve labeled ___.
A
B
C
D
E
F

7.  

Of the seven resistors, the one for which the magnitude of the temperature coefficient of resistance is largest is represented by the curve labeled ___.
A
B
C
D
E
F

8.  

alpha.gif(F) is ___ alpha.gif(E).
more than
equal to
less than
incomparable with

9.  

alpha.gif(B) is ___ alpha.gif (E).
more than
equal to
less than
incomparable with

10.  

alpha.gif (E) is ___ alpha.gif (C).
more than
equal to
less than
incomparable with

11.  

The following information pertains to questions 11-21.

In the circuit below and to the right R1 < R2 < R3 < R4 and each resistor has the same maximum power dissipation capability, Po. The potential difference across, the current through and the rate at which heat is being created within the jth resistor are Vj, Ij and Hj respectively.

V1 is ___ V4.
more than
less than
equal to
incomparable, without additional information, with

12.  

V2 is ___ V3.
more than
less than
equal to
incomparable, without additional information, with

13.  

V2 is ___ V4.
more than
less than
equal to
incomparable, without additional information, with

14.  

I2 is ___ I3.
equal to
more than
less than
incomparable, without additional information, with

15.  

I2 is ___ I1.
equal to
more than
less than
incomparable, without additional information, with

16.  

I1 is ___ I4.
equal to
more than
less than
incomparable, without additional information, with

17.  

H1 is ___ H4.
less than
equal to
more than
incomparable, without additional information, with

18.  

H3 is ___ H4.
less than
equal to
more than
incomparable, without additional information, with

19.  

H2 is ___ H3.
less than
equal to
more than
incomparable, without additional information, with

20.  

If the resistance of R1 was increased slightly, V4 would ___.
remain constant
decrease
increase
be unpredictable

21.  

If the resistance of R1 was increased slightly, V1 would ___.
remain constant
decrease
increase
be unpredictable

22.  

The following information pertains to questions 22-24.

The current through a resistor is measured as a function of the potential difference across the resistor for three individual resistors, the series combination of the three resistors and the parallel combination of the three resistors. The results of the five sets of measurements are shown in the figure at the right.

The parallel combination of the three resistors is represented by the curve labeled ___.
A
B
C
D
E

23.  

The individual resistor which has the smallest resistance is represented by the curve labeled ___.
A
B
C
D
E

24.  

The series combination of the three resistors is represented by the curve labeled ___.
A
B
C
D
E


Bosworth et al, ARCO MCAT SuperCourse (MacMillan, 1997). Copyright 1997, 1996, 1994, 1991 by Stefan Bosworth, Ronald Drucker, Edgar Schnebel, Denise Garlan, Rosie Soy and Marion Brisk. Used by permission of MacMillan, Inc.

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The Virtual Prof's Physics Study Guide for the MCAT. Copyright 1997 by Glen Terrell and RonJon Publishing, Inc. Used by permission of Glen Terrell. For more information, go to http://www.virtualprof.com.


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