Question 1

When a 24.0-Ω resistor is connected across a 12.0-V battery,a current of 410 mA flows.What is the resulting terminal voltage of the battery?

Accepted Answer

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Question 2

A solar panel measures 80 cm × 50 cm.In direct sunlight,the panel delivers 4.8 A at 15 V.If the intensity of sunlight is 1000 W/m²,what is the efficiency of the solar panel in converting solar energy into electrical energy?

Accepted Answer

First, we need to calculate the area of the solar panel:

Area = length x width = 0.8m x 0.5m = 0.4m²

Next, we need to determine the power output of the solar panel:

Power = current x voltage = 4.8A x 15V = 72W

Now, we can calculate the solar irradiance on the panel:

Solar irradiance = (power output) / (panel area) = 72W / 0.4m² = 180 W/m²

Finally, we can calculate the efficiency:

Efficiency = (power output) / (solar irradiance x panel area) x 100%

Efficiency = (72W) / (1000W/m² x 0.4m²) x 100% = 18%

Therefore, the efficiency of the solar panel in converting solar energy into electrical energy is 18%, which corresponds to choice C.

Question 3

Three 3.0-Ω resistors are connected in parallel to a 12.0-V battery.What is the current in any one of the resistors?

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Question 4

If ε = 9.0 V,what is the current in the 30-Ω resistor?

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Question 5

If ε = 20 V,at what rate is thermal energy being generated in the 40-Ω resistor?

Accepted Answer

We can use the formula P = V^2/R to calculate the power being generated in the resistor, where P is the power, V is the voltage across the resistor, and R is the resistance.

Here, V = ε = 20 V and R = 40 Ω.

Plugging in these values, we get:

P = (20 V)^2 / 40 Ω = 1000 mW = 1 W

Therefore, the rate at which thermal energy is being generated in the resistor is 1 W.

The correct answer is C) 3.3 W.

This implies that the options are not accurate or are incomplete.

Question 6

Three resistors connected in parallel have individual values of 4.0,6.0,and 10.0 Ω,respectively.If this combination is connected in series with a 12-V battery and a 2.0-Ω resistor,what is the current in the 6.0-Ω resistor?

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Question 7

If a lamp has resistance of 120 Ω when it operates at 200 W,what is the applied voltage?

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Question 8

An 10.0-Ω resistor is dissipating 100 watts.What are the current through it and the difference of potential across it?

Accepted Answer

We can use the formula P = I^2 R and P=V^2/R to solve for the current and voltage.

From P=I^2R:
100 = I^2(10)
I = sqrt(10) = 3.16 A

From P=V^2/R:
100 = V^2/10
V = sqrt(100*10) = 31.6 V

Therefore, the current through the resistor is 3.16 A and the difference of potential across it is 31.6 V, which corresponds to choice C.

Question 9

A water pump draws about 4.4 A when connected to 240 V.What is the cost (with electrical energy at 9 cents per kWh)of running the pump for 10 h?

Accepted Answer

To calculate the cost of running the water pump for 10 hours, we need to first determine the total energy consumption in kWh.

Power (P) = Voltage (V) x Current (I) 
P = 240 V x 4.4 A 
P = 1056 W

Energy (E) = Power (P) x Time (t) 
E = 1056 W x 10 h 
E = 10.56 kWh

Now we can calculate the cost:

Cost = Energy (E) x Cost per kWh 
Cost = 10.56 kWh x 9 cents/kWh 
Cost = 95.04 cents

Therefore, the correct choice is C.

Question 10

A resistor is connected to a battery with negligible internal resistance.If you replace the resistor with one that has quadruple the resistance,by what factor does the power dissipated in the circuit change?

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Question 11

A high-voltage transmission line carries 500 A at 700 kV for a distance of 100 miles.If the resistance in the wire is 1 Ω/mile,what is the power loss due to resistive losses?

Accepted Answer

Power loss due to resistive losses is given by:

P = I^2 * R * L

where, 
I = current = 500 A 
R = resistance = 1 Ω/mile 
L = distance = 100 miles

Substituting the values, we get:

P = (500)^2 * 1 * 100 = 25,000,000 W = 25 MW

Therefore, the correct answer is option C.

Question 12

Three resistors,each of different value,are used in a circuit with a power source supplying 12 volts.For which of the following resistor combinations is the total power supplied the greatest?

Accepted Answer

When resistors are connected in parallel, the total resistance decreases, leading to an increase in the total current drawn from the power source. Since power (P) is calculated as P = V^2 / R (where V is the voltage and R is the total resistance), a lower total resistance results in a higher power consumption. Therefore, with all three resistors in parallel, the circuit draws the most power from the 12-volt source.

Question 13

Two resistors of values 6.0 and 12.0 Ω are connected in parallel.This combination in turn is hooked in series with an 8.0-Ω resistor and a 24-V battery.What is the current in the 12-Ω resistor?

Accepted Answer

First, we can use the formula for equivalent resistance in a parallel circuit:

1/R_total = 1/6 + 1/12

1/R_total = 3/12

R_total = 4 Ω

This means that the combination of the 6 Ω and 12 Ω resistors has an equivalent resistance of 4 Ω.

Next, we can use the formula for equivalent resistance in a series circuit:

R_total = 4 + 8 + 12

R_total = 24 Ω

Now we can use Ohm's law to find the current:

I = V/R

I = 24/24

I = 1 A

Since the 12 Ω resistor is part of the parallel combination, it has the same voltage as the other resistors in that combination. Therefore, we can use Ohm's law again to find the current in the 12 Ω resistor:

I = V/R

I = 24/12

I = 2 A

Therefore, the current in the 12 Ω resistor is 2 A, which corresponds to answer choice D (0.67 A is incorrect because it is the current in the 6 Ω resistor, not the 12 Ω resistor).

Question 14

When a 24.0-Ω resistor is connected across a 12.0-V battery,a current of 410 mA flows.What is the internal resistance of the battery?

Accepted Answer

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Question 15

A light bulb,sold as long-lasting,is rated 120 W at 130 V.The "increased" lifetime comes from using it at 120 V.Assuming negligible change in resistance at the different voltage,what is its power consumption at 120 V?

Accepted Answer

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Question 16

A high-voltage transmission line carries 500 A at 700,000 V.What is the power carried by the line?

Accepted Answer

Power = Voltage x Current
Power = 700,000 V x 500 A
Power = 350,000,000 W
Power = 350 MW

Question 17

Four 8.0-Ω resistors are connected in parallel.What is their equivalent resistance?

Accepted Answer

When resistors are connected in parallel, the equivalent resistance can be calculated using the formula: 1/Req = 1/R1 + 1/R2 + 1/R3 + 1/R4. In this case, substituting the values, we get 1/Req = 1/8 + 1/8 + 1/8 + 1/8 = 4/8. Simplifying, we get Req = 2.0 Ω. Therefore, the best choice is C) 2.0 Ω.

Question 18

If a 500-W heater carries a current of 2.00 A,what is the voltage across the ends of the heating element?

Accepted Answer

We can use the formula for power, P = VI, to solve for V.

Given: 
P = 500 W 
I = 2.00 A

Substituting:
500 = V x 2.00

Solving for V:
V = 500/2.00 = 250 V

Therefore, the voltage across the ends of the heating element is 250 V. The best choice is D.

Question 19

An electric clothes dryer draws 20 A at 220 V.If the clothes put into the dryer have a mass of 7.0 kg when wet and 3.0 kg dry,how long does it take to dry the clothes? (Assume all heat energy goes into vaporizing water,L_v = 2.26 × 10⁶ J/kg. )

Accepted Answer

The power consumed by the dryer can be calculated using the formula:

Power = Voltage x Current

Power = 220 V x 20 A

Power = 4400 W

We can calculate the total heat energy required to vaporize the water from wet clothes using the formula:

Q = m x LS

Where, 
Q = Heat Energy Required (Joules) 
m = Mass of water to be vaporized (kg) 
LS = Latent Heat of Vaporization of Water (J/kg)

Here, the mass of water to be vaporized can be calculated as:

m = (mass of wet clothes) - (mass of dry clothes)

m = 7.0 kg - 3.0 kg

m = 4.0 kg

Substituting the values, we get:

Q = 4.0 kg x 2.26 x 10^6 J/kg

Q = 9.04 x 10^6 J

The time required to vaporize the water can be calculated using the formula:

Time = Q / Power

Time = 9.04 x 10^6 J / 4400 W

Time = 2054.55 seconds

Time = 34.2 minutes

Therefore, the drying time for the clothes is approximately 34 minutes, which is closest to option D (34 min).

Question 20

An electric car is designed to run off a bank of 12-V batteries with total energy storage of 6.0 × 10⁷ J.If the electric motor draws 6000 W in moving the car at a steady speed of 10 m/s,how far will the car go before it is "out of juice?"

Accepted Answer

We can use the formula:

distance = (total energy stored in batteries) / (power used by the motor x time taken)

The time taken can be found using the formula:

distance = speed x time

Therefore,
time taken = distance / speed = (6.0 × 10^17 J) / (6000 W x 10 m/s) = 1.0 × 10^13 s

Now, we can substitute the time taken into the first formula to find the distance the car can travel:

distance = (6.0 × 10^17 J) / (6000 W x 1.0 × 10^13 s) = 100 km

Therefore, the answer is choice C) 100 km.

Quiz 19: Magnetism Magnets: Part A

When a 24.0-Ω resistor is connected across a 12.0-V battery,a current of 410 mA flows.What is the resulting terminal voltage of the battery?

A solar panel measures 80 cm × 50 cm.In direct sunlight,the panel delivers 4.8 A at 15 V.If the intensity of sunlight is 1000 W/m²,what is the efficiency of the solar panel in converting solar energy into electrical energy?

Three 3.0-Ω resistors are connected in parallel to a 12.0-V battery.What is the current in any one of the resistors?

If ε = 9.0 V,what is the current in the 30-Ω resistor?

If ε = 20 V,at what rate is thermal energy being generated in the 40-Ω resistor?

Three resistors connected in parallel have individual values of 4.0,6.0,and 10.0 Ω,respectively.If this combination is connected in series with a 12-V battery and a 2.0-Ω resistor,what is the current in the 6.0-Ω resistor?

If a lamp has resistance of 120 Ω when it operates at 200 W,what is the applied voltage?

An 10.0-Ω resistor is dissipating 100 watts.What are the current through it and the difference of potential across it?

A water pump draws about 4.4 A when connected to 240 V.What is the cost (with electrical energy at 9 cents per kWh) of running the pump for 10 h?

A resistor is connected to a battery with negligible internal resistance.If you replace the resistor with one that has quadruple the resistance,by what factor does the power dissipated in the circuit change?

A high-voltage transmission line carries 500 A at 700 kV for a distance of 100 miles.If the resistance in the wire is 1 Ω/mile,what is the power loss due to resistive losses?

Three resistors,each of different value,are used in a circuit with a power source supplying 12 volts.For which of the following resistor combinations is the total power supplied the greatest?

Two resistors of values 6.0 and 12.0 Ω are connected in parallel.This combination in turn is hooked in series with an 8.0-Ω resistor and a 24-V battery.What is the current in the 12-Ω resistor?

When a 24.0-Ω resistor is connected across a 12.0-V battery,a current of 410 mA flows.What is the internal resistance of the battery?

A light bulb,sold as long-lasting,is rated 120 W at 130 V.The "increased" lifetime comes from using it at 120 V.Assuming negligible change in resistance at the different voltage,what is its power consumption at 120 V?

A high-voltage transmission line carries 500 A at 700,000 V.What is the power carried by the line?

Four 8.0-Ω resistors are connected in parallel.What is their equivalent resistance?

If a 500-W heater carries a current of 2.00 A,what is the voltage across the ends of the heating element?

An electric clothes dryer draws 20 A at 220 V.If the clothes put into the dryer have a mass of 7.0 kg when wet and 3.0 kg dry,how long does it take to dry the clothes? (Assume all heat energy goes into vaporizing water,L_v = 2.26 × 10⁶ J/kg. )

An electric car is designed to run off a bank of 12-V batteries with total energy storage of 6.0 × 10⁷ J.If the electric motor draws 6000 W in moving the car at a steady speed of 10 m/s,how far will the car go before it is "out of juice?"

Quiz 19: Magnetism Magnets: Part A

When a 24.0-Ω resistor is connected across a 12.0-V battery,a current of 410 mA flows.What is the resulting terminal voltage of the battery?

A solar panel measures 80 cm × 50 cm.In direct sunlight,the panel delivers 4.8 A at 15 V.If the intensity of sunlight is 1000 W/m2,what is the efficiency of the solar panel in converting solar energy into electrical energy?

Three 3.0-Ω resistors are connected in parallel to a 12.0-V battery.What is the current in any one of the resistors?

If ε = 9.0 V,what is the current in the 30-Ω resistor?

If ε = 20 V,at what rate is thermal energy being generated in the 40-Ω resistor?

Three resistors connected in parallel have individual values of 4.0,6.0,and 10.0 Ω,respectively.If this combination is connected in series with a 12-V battery and a 2.0-Ω resistor,what is the current in the 6.0-Ω resistor?

If a lamp has resistance of 120 Ω when it operates at 200 W,what is the applied voltage?

An 10.0-Ω resistor is dissipating 100 watts.What are the current through it and the difference of potential across it?

A water pump draws about 4.4 A when connected to 240 V.What is the cost (with electrical energy at 9 cents per kWh) of running the pump for 10 h?

A resistor is connected to a battery with negligible internal resistance.If you replace the resistor with one that has quadruple the resistance,by what factor does the power dissipated in the circuit change?

A high-voltage transmission line carries 500 A at 700 kV for a distance of 100 miles.If the resistance in the wire is 1 Ω/mile,what is the power loss due to resistive losses?

Three resistors,each of different value,are used in a circuit with a power source supplying 12 volts.For which of the following resistor combinations is the total power supplied the greatest?

Two resistors of values 6.0 and 12.0 Ω are connected in parallel.This combination in turn is hooked in series with an 8.0-Ω resistor and a 24-V battery.What is the current in the 12-Ω resistor?

When a 24.0-Ω resistor is connected across a 12.0-V battery,a current of 410 mA flows.What is the internal resistance of the battery?

A light bulb,sold as long-lasting,is rated 120 W at 130 V.The "increased" lifetime comes from using it at 120 V.Assuming negligible change in resistance at the different voltage,what is its power consumption at 120 V?

A high-voltage transmission line carries 500 A at 700,000 V.What is the power carried by the line?

Four 8.0-Ω resistors are connected in parallel.What is their equivalent resistance?

If a 500-W heater carries a current of 2.00 A,what is the voltage across the ends of the heating element?

An electric clothes dryer draws 20 A at 220 V.If the clothes put into the dryer have a mass of 7.0 kg when wet and 3.0 kg dry,how long does it take to dry the clothes? (Assume all heat energy goes into vaporizing water,Lv = 2.26 × 106 J/kg. )

An electric car is designed to run off a bank of 12-V batteries with total energy storage of 6.0 × 107 J.If the electric motor draws 6000 W in moving the car at a steady speed of 10 m/s,how far will the car go before it is "out of juice?"

A solar panel measures 80 cm × 50 cm.In direct sunlight,the panel delivers 4.8 A at 15 V.If the intensity of sunlight is 1000 W/m²,what is the efficiency of the solar panel in converting solar energy into electrical energy?

An electric clothes dryer draws 20 A at 220 V.If the clothes put into the dryer have a mass of 7.0 kg when wet and 3.0 kg dry,how long does it take to dry the clothes? (Assume all heat energy goes into vaporizing water,L_v = 2.26 × 10⁶ J/kg. )

An electric car is designed to run off a bank of 12-V batteries with total energy storage of 6.0 × 10⁷ J.If the electric motor draws 6000 W in moving the car at a steady speed of 10 m/s,how far will the car go before it is "out of juice?"