PHY131 EXAM 2 CMU QUESTIONS AND CORRECT
DETAILED ANSWERS (VERIFIED ANSWERS) |ALREADY
GRADED A+||BRAND NEW
Kirchoff's Law Ans✓✓✓ Laws for analyzing circuits
Junction Rule Ans✓✓✓ The sum of the currents entering a junction
must equal the sum of the currents leaving the junction
Loop (or Sum) Rule Ans✓✓✓ The sum of the potential differences
(voltage) around any closed loop must be zero
Steps to solving loop problems Ans✓✓✓ Assign currents and direction
to each part of the circuit (direction you just guess), apply the junction
rule at each junction, apply the loop rule at each CLOSED loop, you get
a system of equations for the unknowns-which are the currents
V=-IR (negative = voltage decrease) Ans✓✓✓ voltage when the
direction around the loop is the same as the current
V=+IR (positive = voltage increase) Ans✓✓✓ voltage when the
direction around the loop is AGAINST the current
V=+Vb (positive = voltage increase) Ans✓✓✓ Direction around the
loop goes from the negative terminal to the positive terminal
, V=-Vb (negative = voltage decrease) Ans✓✓✓ Direction around the
loop goes from the positive to the negative terminal
RC Circuits Ans✓✓✓ Circuits with both a resistor and capacitor
0 Ans✓✓✓ What is the initial charge AND voltage across a capacitor in
an RC circuit?
V=-Q/c Ans✓✓✓ As charge builds up on the capacitor, what is the
voltage change?
V=IR Ans✓✓✓ What is the voltage change across the resistor?
equals the voltage of the battery Ans✓✓✓ A capacitor will charge up
until the voltage change across the capacitor:
drops steadily (and exponentially) Ans✓✓✓ As a capacitor charges, the
current:
transcendental number Ans✓✓✓ infinite numbers that never repeat
y=e^x Ans✓✓✓ exponential function
DETAILED ANSWERS (VERIFIED ANSWERS) |ALREADY
GRADED A+||BRAND NEW
Kirchoff's Law Ans✓✓✓ Laws for analyzing circuits
Junction Rule Ans✓✓✓ The sum of the currents entering a junction
must equal the sum of the currents leaving the junction
Loop (or Sum) Rule Ans✓✓✓ The sum of the potential differences
(voltage) around any closed loop must be zero
Steps to solving loop problems Ans✓✓✓ Assign currents and direction
to each part of the circuit (direction you just guess), apply the junction
rule at each junction, apply the loop rule at each CLOSED loop, you get
a system of equations for the unknowns-which are the currents
V=-IR (negative = voltage decrease) Ans✓✓✓ voltage when the
direction around the loop is the same as the current
V=+IR (positive = voltage increase) Ans✓✓✓ voltage when the
direction around the loop is AGAINST the current
V=+Vb (positive = voltage increase) Ans✓✓✓ Direction around the
loop goes from the negative terminal to the positive terminal
, V=-Vb (negative = voltage decrease) Ans✓✓✓ Direction around the
loop goes from the positive to the negative terminal
RC Circuits Ans✓✓✓ Circuits with both a resistor and capacitor
0 Ans✓✓✓ What is the initial charge AND voltage across a capacitor in
an RC circuit?
V=-Q/c Ans✓✓✓ As charge builds up on the capacitor, what is the
voltage change?
V=IR Ans✓✓✓ What is the voltage change across the resistor?
equals the voltage of the battery Ans✓✓✓ A capacitor will charge up
until the voltage change across the capacitor:
drops steadily (and exponentially) Ans✓✓✓ As a capacitor charges, the
current:
transcendental number Ans✓✓✓ infinite numbers that never repeat
y=e^x Ans✓✓✓ exponential function
