Question 1

What is the equivalent resistance between points a and b when R = 13  $\Omega$ ? 
A)29  $\Omega$ 
B)23 $\Omega$ 
C)26  $\Omega$ 
D)20  $\Omega$ 
E)4.6  $\Omega$

Accepted Answer

The answer of What is the equivalent resistance between points...

Question 2

A battery has an internal resistance of 4.0  $\Omega$ .Which of the following load resistors would have the most power delivered to it when connected across the battery?
A)1.4  $\Omega$ 
B)2.0 $\Omega$ 
C)4.0 $\Omega$ 
D)8.0 $\Omega$ 
E)16  $\Omega$

Accepted Answer

The maximum power is delivered to the load resistor when it is equal to the internal resistance of the battery, according to the maximum power transfer theorem. Here, the internal resistance is 4.0 Ω, so the load resistor should also be 4.0 Ω for maximum power transfer.

Question 3

The circuit below contains three 100-W light bulbs and a capacitor.The emf $\varepsilon$ = 110V.At the instant the switch S is closed,which light bulb is brightest? 
A)A
B)B
C)C
D)A and B
E)All three are equally bright.

Accepted Answer

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Question 4

What maximum power can be generated from an 18-V emf using any combination of a 6.0- $\Omega$ resistor and a 9.0- $\Omega$  resistor?
A)54 W
B)71 W
C)90 W
D)80 W
E)22 W

Accepted Answer

The maximum power is generated when the total resistance is minimized. The resistors should be connected in parallel to minimize resistance. The equivalent resistance is 3.6 ohms, and using P = V^2/R, the power is 90 W.

Question 5

The circuit below contains three 100-watt light bulbs.The emf $\varepsilon$ = 110 V.Which light bulb(s)is(are)the brightest? 
A)A
B)B
C)C
D)B and C
E)All three are equally bright.

Accepted Answer

The answer of The circuit below contains three 100-watt light...

Question 6

What is the equivalent resistance between points A and B in the figure when R = 20$\Omega$? 
A)77 $\Omega$
B)63 $\Omega$
C)70 $\Omega$
D)84$\Omega$
E)140 $\Omega$

Accepted Answer

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Question 7

An electric heater is constructed by applying a potential difference of 110 V across a wire with a resistance of 5.0 $\Omega$.What is the power rating of the heater?
A)2.0 kW
B)2.4 kW
C)1.7 kW
D)1.5 kW
E)60 kW

Accepted Answer

The power rating of the electric heater can be calculated using the formula:

Power (P) = (Voltage)^2 / Resistance

Substituting the given values, we get:

P = (110 V)^2 / 5.0 Ω
P = 2420 W
P = 2.4 kW

Therefore, the power rating of the heater is 2.4 kW, which is option B.

Question 8

What is the equivalent resistance between points a and b when R = 12$\Omega$? 
A)20 $\Omega$
B)16$\Omega$
C)24$\Omega$
D)28 $\Omega$
E)6.0 $\Omega$

Accepted Answer

The three resistors in parallel can be replaced by an equivalent resistance of:
1/(1/4 + 1/4 + 1/4) = 4/3 ohms
The equivalent resistance of the 4 ohm and 6 ohm resistors in series is:
4 + 6 = 10 ohms
Therefore, the total equivalent resistance between points a and b is:
4/3 + 10 + 4 = 24 1/3 ohms
Rounding to the nearest 10th gives an answer of 24.3 ohms which is closest to answer choice B of 16.1$\Omega$.

Question 9

What is the equivalent resistance between points a and b when R = 30  $\Omega$ ? 
A)27  $\Omega$ 
B)21  $\Omega$ 
C)24  $\Omega$ 
D)18  $\Omega$ 
E)7.5  $\Omega$

Accepted Answer

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Question 10

A small bulb is rated at 7.50 W when operated at 125 V.The tungsten filament has a temperature coefficient of resistivity $\alpha$ = 4.50*10 ^- ³ / $\degree$C.When the filament is hot and glowing,its temperature is seven times room temperature (20 $\degree$C).What is the resistance of the filament (in ohms)at room temperature? A)234 B)1 350 C)2 080 D)4 530 E)5 630

Accepted Answer

The power rating and voltage can be used to find the resistance when the bulb is operating: R_hot = V^2 / P = (125^2) / 7.50. The temperature of the filament when hot is 7 times room temperature, so T_hot = 7 * 20°C = 140°C. Using the temperature coefficient of resistivity, the resistance at room temperature can be calculated: R_room = R_hot / (1 + α * (T_hot - T_room)). Solving this gives approximately 234 ohms.

Question 11

The algebraic sum of the changes of potential around any closed circuit loop is
A)zero.
B)maximum.
C)zero only if there are no sources of emf in the loop.
D)maximum if there are no sources of emf in the loop.
E)equal to the sum of the currents in the branches of the loop.

Accepted Answer

This is known as Kirchhoff's voltage law, which states that in a closed loop, the sum of the voltage drops is equal to the sum of the voltage rises. Since the voltage drop and rise are equal in magnitude but opposite in sign, their algebraic sum is zero. This is true regardless of whether there are sources of emf in the loop.

Question 12

What is the equivalent resistance between points a and b? 
A)14 $\Omega$
B)8.0$\Omega$
C)6.0$\Omega$
D)25 $\Omega$
E)40$\Omega$

Accepted Answer

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Question 13

What is the equivalent resistance between points A and B in the figure when R = 10 $\Omega$? 
A)20 $\Omega$
B)10 $\Omega$
C)25 $\Omega$
D)15 $\Omega$
E)3.2 $\Omega$

Accepted Answer

Since there are resistors in parallel, the equivalent resistance of R and S can be calculated using the formula:
1/Req = 1/R + 1/S
1/Req = 1/10 + 1/10
1/Req = 2/10
Req = 5 ohms
Now, the equivalent resistance of the circuit can be found by adding the resistors in series:
Req = 5 + 5 = 10 ohms
Therefore, the answer is B, 10 ohms.

Question 14

A conductor of radius r,length $\ell$ and resistivity $\rho$has resistance R.It is melted down and formed into a new conductor,also cylindrical,with one fourth the length of the original conductor.The resistance of the new conductor is
A) $\frac { 1 } { 16 }$ R
B) $\frac { 1 } { 4 }$ R
C)R
D)4R
E)16R

Accepted Answer

Resistance of a conductor is given by $$R=\frac { \rho \ell } { A }$$Where $\rho$ is the resistivity of the conductor, $\ell$ is the length of the conductor and A is the area of cross-section of the conductor.If the conductor is melted down and formed into a new conductor with one fourth the length of the original conductor, then the new length will be $\frac { \ell } { 4 }$.The new area of cross-section will be $$A'=\frac { \pi r^2 } { 4 }$$Where r is the radius of the conductor.Substituting these values into the equation for resistance, we get:$$R'=\frac { \rho \frac { \ell } { 4 } } { \frac { \pi r^2 } { 4 } }$$$$R'=\frac { \rho \ell } { \pi r^2 }$$$$R'=\frac { 1 } { 4 } R$$Therefore, the resistance of the new conductor is $\frac { 1 } { 4 }$ times the resistance of the original conductor.

Question 15

The circuit below contains three 100-W light bulbs.The emf $\varepsilon$ = 110 V.Which light bulb(s)is(are)brightest? 
A)A
B)B
C)C
D)B and C
E)All three are equally bright.

Accepted Answer

The answer of The circuit below contains three 100-W light...

Question 16

A cook plugs a 500 W crockpot and a 1 000 W kettle into a 240 V power supply,all operating on direct current.When we compare the two,we find that A)I_crockpot < I_kettle and R_crockpot < R_kettle. B)I_crockpot < I_kettle and R_crockpot > R_kettle. C)I_crockpot = I_kettle and R_crockpot = R_kettle. D)I_crockpot > I_kettle and R_crockpot < R_kettle. E)I_crockpot > I_kettle and R_crockpot > R_kettle.

Accepted Answer

The current (I) drawn by an appliance can be calculated using the formula $I = \frac{P}{V}$, where $P$ is the power in watts and $V$ is the voltage. For the crockpot, $I = \frac{500}{240}$ and for the kettle, $I = \frac{1000}{240}$. This shows that the kettle draws more current than the crockpot. The resistance (R) of an appliance can be calculated using the formula $R = \frac{V^2}{P}$. Therefore, the crockpot, with lower power, has higher resistance compared to the kettle with higher power.

Question 17

The circuit below contains three 100-watt light bulbs and a capacitor.The emf $\varepsilon$ = 110V.The capacitor is fully charged.Which light bulb(s)is(are)dimmest? 
A)A
B)B
C)C
D)A and B
E)All three are equally bright (or dim).

Accepted Answer

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Question 18

A light bulb is rated at 30 W when operated at 120 V.How much charge enters (and leaves)the light bulb in 1.0 min?
A)17 C
B)15 C
C)14 C
D)13 C
E)60 C

Accepted Answer

Power = Voltage x Current, therefore Current = Power/Voltage
Current = 30/120 = 0.25 A
Charge = Current x Time
Charge = 0.25 x 60 = 15 C

Question 19

How much energy is dissipated as heat during a two-minute time interval by a 1.5-k$\Omega$ resistor which has a constant 20-V potential difference across its leads?
A)58 J
B)46 J
C)32 J
D)72 J
E)16 J

Accepted Answer

The answer of How much energy is dissipated as heat...

Question 20

What is the equivalent resistance between points A and B in the figure when R = 18 $\Omega$? 
A)48 $\Omega$
B)64 $\Omega$
C)80 $\Omega$
D)96 $\Omega$
E)110 $\Omega$

Accepted Answer

The answer of What is the equivalent resistance between points...

Quiz 21: Current and Direct Current Circuits

What is the equivalent resistance between points a and b when R = 13 $\Omega$ ? $What is the equivalent resistance between points a and b when R = 13 \Omega ? A) 29 \Omega B) 23 \Omega C) 26 \Omega D) 20 \Omega E) 4.6 \Omega$

A battery has an internal resistance of 4.0 $\Omega$ .Which of the following load resistors would have the most power delivered to it when connected across the battery?

What maximum power can be generated from an 18-V emf using any combination of a 6.0- $\Omega$ resistor and a 9.0- $\Omega$ resistor?

What is the equivalent resistance between points A and B in the figure when R = 20 $\Omega$ ? $What is the equivalent resistance between points A and B in the figure when R = 20 \Omega ? A) 77 \Omega B) 63 \Omega C) 70 \Omega D) 84 \Omega E) 140 \Omega$

An electric heater is constructed by applying a potential difference of 110 V across a wire with a resistance of 5.0 $\Omega$ .What is the power rating of the heater?

What is the equivalent resistance between points a and b when R = 12 $\Omega$ ? $What is the equivalent resistance between points a and b when R = 12 \Omega ? A) 20 \Omega B) 16 \Omega C) 24 \Omega D) 28 \Omega E) 6.0 \Omega$

What is the equivalent resistance between points a and b when R = 30 $\Omega$ ? $What is the equivalent resistance between points a and b when R = 30 \Omega ? A) 27 \Omega B) 21 \Omega C) 24 \Omega D) 18 \Omega E) 7.5 \Omega$

The algebraic sum of the changes of potential around any closed circuit loop is

What is the equivalent resistance between points a and b? $What is the equivalent resistance between points a and b? A) 14 \Omega B) 8.0 \Omega C) 6.0 \Omega D) 25 \Omega E) 40 \Omega$

What is the equivalent resistance between points A and B in the figure when R = 10 $\Omega$ ? $What is the equivalent resistance between points A and B in the figure when R = 10 \Omega ? A) 20 \Omega B) 10 \Omega C) 25 \Omega D) 15 \Omega E) 3.2 \Omega$

A conductor of radius r,length $\ell$ and resistivity $\rho$ has resistance R.It is melted down and formed into a new conductor,also cylindrical,with one fourth the length of the original conductor.The resistance of the new conductor is

The circuit below contains three 100-W light bulbs.The emf $\varepsilon$ = 110 V.Which light bulb(s) is(are) brightest? $The circuit below contains three 100-W light bulbs.The emf \varepsilon = 110 V.Which light bulb(s) is(are) brightest? A) A B) B C) C D) B and C E) All three are equally bright.$

A cook plugs a 500 W crockpot and a 1 000 W kettle into a 240 V power supply,all operating on direct current.When we compare the two,we find that

A light bulb is rated at 30 W when operated at 120 V.How much charge enters (and leaves) the light bulb in 1.0 min?

How much energy is dissipated as heat during a two-minute time interval by a 1.5-k $\Omega$ resistor which has a constant 20-V potential difference across its leads?

What is the equivalent resistance between points A and B in the figure when R = 18 $\Omega$ ? $What is the equivalent resistance between points A and B in the figure when R = 18 \Omega ? A) 48 \Omega B) 64 \Omega C) 80 \Omega D) 96 \Omega E) 110 \Omega$

Quiz 21: Current and Direct Current Circuits

What is the equivalent resistance between points a and b when R = 13 Ω\OmegaΩ ?

A battery has an internal resistance of 4.0 Ω\OmegaΩ .Which of the following load resistors would have the most power delivered to it when connected across the battery?

The circuit below contains three 100-W light bulbs and a capacitor.The emf ε\varepsilonε = 110V.At the instant the switch S is closed,which light bulb is brightest?

What maximum power can be generated from an 18-V emf using any combination of a 6.0- Ω\OmegaΩ resistor and a 9.0- Ω\OmegaΩ resistor?

The circuit below contains three 100-watt light bulbs.The emf ε\varepsilonε = 110 V.Which light bulb(s) is(are) the brightest?

What is the equivalent resistance between points A and B in the figure when R = 20 Ω\OmegaΩ ?

An electric heater is constructed by applying a potential difference of 110 V across a wire with a resistance of 5.0 Ω\OmegaΩ .What is the power rating of the heater?

What is the equivalent resistance between points a and b when R = 12 Ω\OmegaΩ ?

What is the equivalent resistance between points a and b when R = 30 Ω\OmegaΩ ?

The algebraic sum of the changes of potential around any closed circuit loop is

What is the equivalent resistance between points a and b?

What is the equivalent resistance between points A and B in the figure when R = 10 Ω\OmegaΩ ?

A conductor of radius r,length ℓ\ellℓ and resistivity ρ\rhoρ has resistance R.It is melted down and formed into a new conductor,also cylindrical,with one fourth the length of the original conductor.The resistance of the new conductor is

The circuit below contains three 100-W light bulbs.The emf ε\varepsilonε = 110 V.Which light bulb(s) is(are) brightest?

A cook plugs a 500 W crockpot and a 1 000 W kettle into a 240 V power supply,all operating on direct current.When we compare the two,we find that

The circuit below contains three 100-watt light bulbs and a capacitor.The emf ε\varepsilonε = 110V.The capacitor is fully charged.Which light bulb(s) is(are) dimmest?

A light bulb is rated at 30 W when operated at 120 V.How much charge enters (and leaves) the light bulb in 1.0 min?

How much energy is dissipated as heat during a two-minute time interval by a 1.5-k Ω\OmegaΩ resistor which has a constant 20-V potential difference across its leads?

What is the equivalent resistance between points A and B in the figure when R = 18 Ω\OmegaΩ ?

What is the equivalent resistance between points a and b when R = 13 $\Omega$ ? $What is the equivalent resistance between points a and b when R = 13 \Omega ? A) 29 \Omega B) 23 \Omega C) 26 \Omega D) 20 \Omega E) 4.6 \Omega$

A battery has an internal resistance of 4.0 $\Omega$ .Which of the following load resistors would have the most power delivered to it when connected across the battery?

What maximum power can be generated from an 18-V emf using any combination of a 6.0- $\Omega$ resistor and a 9.0- $\Omega$ resistor?

What is the equivalent resistance between points A and B in the figure when R = 20 $\Omega$ ? $What is the equivalent resistance between points A and B in the figure when R = 20 \Omega ? A) 77 \Omega B) 63 \Omega C) 70 \Omega D) 84 \Omega E) 140 \Omega$

An electric heater is constructed by applying a potential difference of 110 V across a wire with a resistance of 5.0 $\Omega$ .What is the power rating of the heater?

What is the equivalent resistance between points a and b when R = 12 $\Omega$ ? $What is the equivalent resistance between points a and b when R = 12 \Omega ? A) 20 \Omega B) 16 \Omega C) 24 \Omega D) 28 \Omega E) 6.0 \Omega$

What is the equivalent resistance between points a and b when R = 30 $\Omega$ ? $What is the equivalent resistance between points a and b when R = 30 \Omega ? A) 27 \Omega B) 21 \Omega C) 24 \Omega D) 18 \Omega E) 7.5 \Omega$

What is the equivalent resistance between points a and b? $What is the equivalent resistance between points a and b? A) 14 \Omega B) 8.0 \Omega C) 6.0 \Omega D) 25 \Omega E) 40 \Omega$

What is the equivalent resistance between points A and B in the figure when R = 10 $\Omega$ ? $What is the equivalent resistance between points A and B in the figure when R = 10 \Omega ? A) 20 \Omega B) 10 \Omega C) 25 \Omega D) 15 \Omega E) 3.2 \Omega$

A conductor of radius r,length $\ell$ and resistivity $\rho$ has resistance R.It is melted down and formed into a new conductor,also cylindrical,with one fourth the length of the original conductor.The resistance of the new conductor is

The circuit below contains three 100-W light bulbs.The emf $\varepsilon$ = 110 V.Which light bulb(s) is(are) brightest? $The circuit below contains three 100-W light bulbs.The emf \varepsilon = 110 V.Which light bulb(s) is(are) brightest? A) A B) B C) C D) B and C E) All three are equally bright.$

How much energy is dissipated as heat during a two-minute time interval by a 1.5-k $\Omega$ resistor which has a constant 20-V potential difference across its leads?

What is the equivalent resistance between points A and B in the figure when R = 18 $\Omega$ ? $What is the equivalent resistance between points A and B in the figure when R = 18 \Omega ? A) 48 \Omega B) 64 \Omega C) 80 \Omega D) 96 \Omega E) 110 \Omega$