Upload
claud-hopkins
View
224
Download
6
Tags:
Embed Size (px)
Citation preview
ConcepTest 17.1aConcepTest 17.1a Electric Potential Energy I Electric Potential Energy I 1) proton
2) electron
3) both feel the same force
4) neither – there is no force
5) they feel the same magnitude force but opposite direction
E
electronelectron
protonproton
E
electronelectron
protonproton++
--
A A protonproton and an and an electronelectron are in are in a constant electric field created a constant electric field created by oppositely charged plates. by oppositely charged plates. You release the You release the protonproton from from the the positivepositive side and the side and the electronelectron from the from the negativenegative side. side. Which feels the larger electric Which feels the larger electric force?force?
E
electronelectron
protonproton
E
electronelectron
protonproton++
--
1) proton
2) electron
3) both feel the same acceleration
4) neither – there is no acceleration
5) they feel the same magnitude acceleration but opposite direction
A A protonproton and an and an electronelectron are in are in a constant electric field created a constant electric field created by oppositely charged plates. by oppositely charged plates. You release the You release the protonproton from from the the positivepositive side and the side and the electronelectron from the from the negativenegative side. side. Which has the larger Which has the larger acceleration?acceleration?
ConcepTest 17.1bConcepTest 17.1b Electric Potential Energy II Electric Potential Energy II
E
electronelectron
protonproton
E
electronelectron
protonproton++
--
1) proton
2) electron
3) both acquire the same KE
4) neither – there is no change of KE
5) they both acquire the same KE but with opposite signs
ConcepTest 17.1cConcepTest 17.1c Electric Potential Energy III Electric Potential Energy III
A A protonproton and an and an electronelectron are in are in a constant electric field created a constant electric field created by oppositely charged plates. by oppositely charged plates. You release the You release the protonproton from from the the positivepositive side and the side and the electronelectron from the from the negativenegative side. side. When it strikes the opposite When it strikes the opposite plate, which one has more KE?plate, which one has more KE?
Which two points have Which two points have the the samesame potential? potential?
1) A and C
2) B and E
3) B and D
4) C and E
5) no pair
A
C
B DEQ
ConcepTest 17.6ConcepTest 17.6 Equipotential of Point ChargeEquipotential of Point Charge
ConcepTest 18.1ConcepTest 18.1 Connect the Battery Connect the Battery
Which is the correct way to Which is the correct way to
light the lightbulb with the light the lightbulb with the
battery?battery?
4) all are correct
5) none are correct
1) 3)2)
1) Ohm’s law is obeyed since the current Ohm’s law is obeyed since the current still increases when V increasesstill increases when V increases
2) Ohm’s law is not obeyedOhm’s law is not obeyed
3) This has nothing to do with Ohm’s lawThis has nothing to do with Ohm’s law
ConcepTest 18.2ConcepTest 18.2 Ohm’s Law Ohm’s Law
You double the You double the voltagevoltage
across a certain conductor across a certain conductor
and you observe the and you observe the currentcurrent
increases three times. What increases three times. What
can you conclude?can you conclude?
ConcepTest 18.3aConcepTest 18.3a Wires IWires I
Two wires, Two wires, AA and and BB, are made of the , are made of the
same metalsame metal and have and have equal lengthequal length, ,
but the resistance of wire but the resistance of wire AA is is four four
timestimes the resistance of wire the resistance of wire BB. How . How
do their diameters compare?do their diameters compare?
1) ddAA = 4 = 4 ddBB
2) ddAA = 2 = 2 ddBB
3) ddAA = = ddBB
4) 4) ddAA = 1/2 = 1/2 ddBB
5) 5) ddAA = 1/4 = 1/4 ddBB
ConcepTest 18.3bConcepTest 18.3b Wires II Wires II
A wire of resistance A wire of resistance RR is is
stretched uniformly (keeping its stretched uniformly (keeping its
volume constant) until it is twice volume constant) until it is twice
its original length. What happens its original length. What happens
to the resistance?to the resistance?
1) it decreasesit decreases by a factor 4by a factor 4
2) it decreasesit decreases by a factor 2by a factor 2
3) it stays the sameit stays the same
4) it increases4) it increases by a factor 2by a factor 2
5) it increases5) it increases by a factor 4by a factor 4
ConcepTest 18.4ConcepTest 18.4 Dimmer Dimmer
When you rotate the knob of a When you rotate the knob of a
light dimmer, what is being light dimmer, what is being
changed in the electric circuit?changed in the electric circuit?
1) the power
2) the current
3) the voltage
4) both (1) and (2)
5) both (2) and (3)
ConcepTest 18.5aConcepTest 18.5a LightbulbsLightbulbs
Two lightbulbs operate at 120 V, but one Two lightbulbs operate at 120 V, but one
has a power rating of has a power rating of 25 W25 W while the while the
other has a power rating of other has a power rating of 100 W100 W. .
Which one has the greater resistance? Which one has the greater resistance?
1) the 25 W bulb
2) the 100 W bulb
3) both have the same
4) this has nothing to do with resistance
ConcepTest 18.5bConcepTest 18.5b Space Heaters ISpace Heaters I
Two space heaters in your living Two space heaters in your living
room are operated at 120 V. room are operated at 120 V.
Heater 1 has Heater 1 has twicetwice the resistance the resistance
of heater 2. Which one will give of heater 2. Which one will give
off more heat?off more heat?
1) heater 1
2) heater 2
3) both equally
ConcepTest 19.1aConcepTest 19.1a Series Resistors ISeries Resistors I
9 V
Assume that the voltage of the battery Assume that the voltage of the battery
is is 9 V9 V and that the three resistors are and that the three resistors are
identicalidentical. What is the potential . What is the potential
difference across each resistor?difference across each resistor?
1) 12 V
2) zero
3) 3 V
4) 4 V
5) you need to know the actual value of R
ConcepTest 19.1bConcepTest 19.1b Series Resistors IISeries Resistors II
12 V
R1= 4 R2= 2
In the circuit below, what is the In the circuit below, what is the
voltage across voltage across R1??
1) 12 V
2) zero
3) 6 V
4) 8 V
5) 4 V
ConcepTest 19.2aConcepTest 19.2a Parallel Resistors IParallel Resistors I
In the circuit below, what is the In the circuit below, what is the
current through current through R1??
10 V
R1= 5
R2= 2
1) 10 A
2) zero
3) 5 A
4) 2 A
5) 7 A
ConcepTest 19.2bConcepTest 19.2b Parallel Resistors IIParallel Resistors II
1) increases
2) remains the same
3) decreases
4) drops to zero
Points P and Q are connected to a Points P and Q are connected to a
battery of fixed voltage. As more battery of fixed voltage. As more
resistors resistors RR are added to the parallel are added to the parallel
circuit, what happens to the circuit, what happens to the total total
currentcurrent in the circuit? in the circuit?
ConcepTest 19.3aConcepTest 19.3a Short CircuitShort Circuit
Current flows through a Current flows through a
lightbulb. If a wire is now lightbulb. If a wire is now
connected across the connected across the
bulb, what happens?bulb, what happens?
1) all the current continues to flow through all the current continues to flow through the bulbthe bulb
2) half the current flows through the wire, half the current flows through the wire, the other half continues through the the other half continues through the bulbbulb
3) all the current flows through the wire all the current flows through the wire
4) none of the abovenone of the above
ConcepTest 19.3bConcepTest 19.3b Short Circuit IIShort Circuit II
Two lightbulbs A and B are Two lightbulbs A and B are
connected in series to a connected in series to a
constant voltage source. constant voltage source.
When a wire is connected When a wire is connected
across B, bulb A will:across B, bulb A will:
1) glow brighter than beforeglow brighter than before
2) glow just the same as beforeglow just the same as before
3) glow dimmer than beforeglow dimmer than before
4) go out completely4) go out completely
5) explode5) explode
ConcepTest 19.4aConcepTest 19.4a Circuits ICircuits I
1) circuit 1circuit 1
2) circuit 2circuit 2
3) both the sameboth the same
4) it depends on it depends on RR
The lightbulbs in the circuit below The lightbulbs in the circuit below
are identical with the same are identical with the same
resistance resistance RR. Which circuit . Which circuit
produces more light? (brightness produces more light? (brightness
power) power)
ConcepTest 19.4bConcepTest 19.4b Circuits IICircuits II
1) twice as muchtwice as much
2) the samethe same
3) 1/2 as much1/2 as much
4) 1/4 as much 1/4 as much
5) 4 times as much 4 times as much
10 V10 V
A
B C
The three lightbulbs in the circuit all have The three lightbulbs in the circuit all have
the the same resistance ofsame resistance of 1 1 By how By how
much is the much is the brightness of bulb B brightness of bulb B greater greater
or smaller than the or smaller than the brightness of bulb Abrightness of bulb A? ?
(brightness (brightness power) power)
ConcepTest 19.7ConcepTest 19.7 Junction RuleJunction Rule
1) 2 A
2) 3 A
3) 5 A
4) 6 A
5) 10 A
5 A
8 A
2 A
P
What is the current in branch P?What is the current in branch P?