Question 1

Ten coulombs of charge start from the negative terminal of a battery,flow through the battery and then leave the positive terminal through a wire,flow through a resistor and then return to the starting point on this closed circuit.In this complete process,the ten coulombs:

Accepted Answer

When the charge flows from the negative terminal of the battery to the positive terminal, it gains potential energy. As it flows through the resistor, it loses potential energy and this energy is dissipated as heat energy. However, when the charge flows back to the starting point of the circuit, it returns to its initial potential energy level. Therefore, the net change in potential energy is zero, and the correct answer is D.

Question 2

The unit for rate of energy transformation,the watt,in an electric circuit is equivalent to which of the following?

Accepted Answer

The watt is the unit of power, which is the rate of energy transformation per unit time. In an electric circuit, power is calculated as the product of voltage and current, therefore the unit of power is the product of the units of voltage and current, i.e., V⋅A.

Question 3

An electric toaster requires 900 W at 100 V.What is the resistance of the heating coil?

Accepted Answer

We can use Ohm's Law to solve this problem. 
Ohm's Law states: V = IR, where V is the voltage, I is the current, and R is the resistance.

We are given the power (P) and the voltage (V). We can use the following equation to find the current (I): 
P = IV

We can then rearrange Ohm's Law to solve for R: 
R = V/I

Plugging in the given values, we get: 
I = P/V = 900/100 = 9 A 
R = V/I = 100/9 = 11.1 Ω

Rounding to the nearest whole number, the answer is 11 Ω.

Question 4

Which process will double the power given off by a resistor?

Accepted Answer

The answer of Which process will double the power given...

Question 5

A light bulb has resistance of 210 Ω when operating at 105 V.Find the current in the light bulb.

Accepted Answer

We can use Ohm's law, which states that the current (I) through a device is equal to the voltage (V) across the device divided by its resistance (R):

I = V/R

Substituting the given values, we get:

I = 105 V / 210 Ω = 0.5 A

Therefore, the answer is choice C) 0.5 A.

Question 6

A light bulb,sold as long-lasting,is rated 95 W at 145 V.The "increased" lifetime comes from using it at 105 V.Assuming negligible change in resistance at the different voltage,what is its power consumption at 105 V?

Accepted Answer

The power consumption can be calculated using the formula P = V^2 / R. First, find the resistance using the rated values: R = (145 V)^2 / 95 W. Then, use this resistance to find the power at 105 V: P = (105 V)^2 / R, which gives approximately 50 W.

Question 7

If a lamp has a resistance of 105 Ω when it operates at 100 W,what current does it carry?

Accepted Answer

The lamp operates at a power of P = 100 W and has a resistance of R = 105 Ω. 
Using the formula P = I^2 * R, we can solve for the current I:

I = sqrt(P/R) = sqrt(100/105) = 0.98 A

Therefore, the correct answer is choice C.

Question 8

A 400-W heater carries a current of 4.0 A.How much does it cost to operate the heater for 50 min if electrical energy costs 6 cents per kWh?

Accepted Answer

The answer of A 400-W heater carries a current of...

Question 9

If electrical energy costs 4 cents per kWh,what does it cost to heat 210 kg water from 30°C to 65°C? (The specific heat of water = 10³ cal/kg⋅°C and 1.0 cal = 4.186 J. )

Accepted Answer

The answer of If electrical energy costs 4 cents per...

Question 10

The quantity volt is equivalent to which of the following?

Accepted Answer

The volt is defined as the potential difference across a conductor when a current of one ampere dissipates one watt of power. In terms of units, this can be expressed as J/C or joules per coulomb. Therefore, the correct equivalent option is D) J/C.

Question 11

If a 500-W heater carries a current of 4.00 A,what is the resistance of the heating element?

Accepted Answer

The resistance can be calculated using the formula $P = I^2R$, where $P$ is the power (500 W), $I$ is the current (4.00 A), and $R$ is the resistance. Rearranging the formula to solve for $R$ gives $R = P / I^2$. Substituting the given values, $R = 500 / (4.00)^2 = 500 / 16 = 31.25 \Omega$, which rounds to 31.3 Ω.

Question 12

An electric clothes dryer draws 23 A at 220 V.If the clothes put into the dryer have a mass of 7 kg when wet and 4 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 answer of An electric clothes dryer draws 23 A...

Question 13

A steam turbine at an electric power plant delivers 4,600 kW of power to an electrical generator which converts 85% of this mechanical energy into electrical energy.What is the current delivered by the generator if it delivers at 3,200 V?

Accepted Answer

We can start by using the formula:

Power (P) = Voltage (V) x Current (I)

We can rearrange this formula to solve for the current:

I = P / V

First, we need to find the electrical power output of the generator, which is:

Electrical Power = Mechanical Power x Efficiency

Electrical Power = 4,600 kW x 0.85
Electrical Power = 3,910 kW

Now we can calculate the current:

I = 3,910 kW / 3,200 V
I ≈ 1,219 A

To put this in scientific notation, we get:

I ≈ 1.2 x 10^3 A

Therefore, the answer is C.

Question 14

A 55-W light bulb is in a socket supplied with 100 V.What is the current in the bulb?

Accepted Answer

The power (P) is given by P = VI, where V is voltage and I is current. Rearranging gives I = P/V = 55W/100V = 0.55 A, which is approximately 0.6 A.

Question 15

If a 550-W heater carries a current of 3 A,what is the voltage across the ends of the heating element?

Accepted Answer

We can use the formula P = VI, where P is the power in watts, V is the voltage in volts, and I is the current in amperes. In this case, P = 550 W and I = 3 A, so we can solve for V:

V = P/I = 550 W / 3 A = 183.3 V.

Therefore, the answer is B.

Question 16

If a lamp has resistance of 110 Ω when it operates at 100 W,what is the applied voltage?

Accepted Answer

The answer of If a lamp has resistance of 110...

Question 17

The temperature coefficient of resistivity for a "perfect" ohmic material would be:

Accepted Answer

A "perfect" ohmic material would have a constant resistivity, meaning that its resistance would not change with temperature. Therefore, the temperature coefficient of resistivity would be zero.

Question 18

The heating coil of a hot water heater has a resistance of 25 Ω and operates at 220 V.How long a time is required to raise the temperature of 150kg of water from 25°C to 85°C? (The specific heat for water = 10³ cal/kg⋅°C and 1.0 cal = 4.186 J).

Accepted Answer

The answer of The heating coil of a hot water...

Question 19

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?

Accepted Answer

The power dissipated in a resistor is given by P = V^2/R. If the resistance is quadrupled, the power becomes P' = V^2/(4R) = P/4. Thus, the power is reduced by a factor of 0.25.

Question 20

If a 12-V battery,with negligible internal resistance,and an 20-Ω resistor are connected in series,what is the amount of electrical energy transformed to heat per coulomb of charge that flows through the circuit?

Accepted Answer

The electrical energy transformed to heat per coulomb of charge is equal to the voltage of the battery, which is 12 V, hence 12 J per coulomb.

Quiz 17: Current and Resistance Electric Current

Ten coulombs of charge start from the negative terminal of a battery,flow through the battery and then leave the positive terminal through a wire,flow through a resistor and then return to the starting point on this closed circuit.In this complete process,the ten coulombs:

The unit for rate of energy transformation,the watt,in an electric circuit is equivalent to which of the following?

An electric toaster requires 900 W at 100 V.What is the resistance of the heating coil?

Which process will double the power given off by a resistor?

A light bulb has resistance of 210 Ω when operating at 105 V.Find the current in the light bulb.

A light bulb,sold as long-lasting,is rated 95 W at 145 V.The "increased" lifetime comes from using it at 105 V.Assuming negligible change in resistance at the different voltage,what is its power consumption at 105 V?

If a lamp has a resistance of 105 Ω when it operates at 100 W,what current does it carry?

A 400-W heater carries a current of 4.0 A.How much does it cost to operate the heater for 50 min if electrical energy costs 6 cents per kWh?

If electrical energy costs 4 cents per kWh,what does it cost to heat 210 kg water from 30°C to 65°C? (The specific heat of water = 10³ cal/kg⋅°C and 1.0 cal = 4.186 J. )

The quantity volt is equivalent to which of the following?

If a 500-W heater carries a current of 4.00 A,what is the resistance of the heating element?

An electric clothes dryer draws 23 A at 220 V.If the clothes put into the dryer have a mass of 7 kg when wet and 4 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) .

A steam turbine at an electric power plant delivers 4,600 kW of power to an electrical generator which converts 85% of this mechanical energy into electrical energy.What is the current delivered by the generator if it delivers at 3,200 V?

A 55-W light bulb is in a socket supplied with 100 V.What is the current in the bulb?

If a 550-W heater carries a current of 3 A,what is the voltage across the ends of the heating element?

If a lamp has resistance of 110 Ω when it operates at 100 W,what is the applied voltage?

The temperature coefficient of resistivity for a "perfect" ohmic material would be:

The heating coil of a hot water heater has a resistance of 25 Ω and operates at 220 V.How long a time is required to raise the temperature of 150kg of water from 25°C to 85°C? (The specific heat for water = 10³ cal/kg⋅°C and 1.0 cal = 4.186 J) .

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?

If a 12-V battery,with negligible internal resistance,and an 20-Ω resistor are connected in series,what is the amount of electrical energy transformed to heat per coulomb of charge that flows through the circuit?

Quiz 17: Current and Resistance Electric Current

Ten coulombs of charge start from the negative terminal of a battery,flow through the battery and then leave the positive terminal through a wire,flow through a resistor and then return to the starting point on this closed circuit.In this complete process,the ten coulombs:

The unit for rate of energy transformation,the watt,in an electric circuit is equivalent to which of the following?

An electric toaster requires 900 W at 100 V.What is the resistance of the heating coil?

Which process will double the power given off by a resistor?

A light bulb has resistance of 210 Ω when operating at 105 V.Find the current in the light bulb.

A light bulb,sold as long-lasting,is rated 95 W at 145 V.The "increased" lifetime comes from using it at 105 V.Assuming negligible change in resistance at the different voltage,what is its power consumption at 105 V?

If a lamp has a resistance of 105 Ω when it operates at 100 W,what current does it carry?

A 400-W heater carries a current of 4.0 A.How much does it cost to operate the heater for 50 min if electrical energy costs 6 cents per kWh?

If electrical energy costs 4 cents per kWh,what does it cost to heat 210 kg water from 30°C to 65°C? (The specific heat of water = 103 cal/kg⋅°C and 1.0 cal = 4.186 J. )

The quantity volt is equivalent to which of the following?

If a 500-W heater carries a current of 4.00 A,what is the resistance of the heating element?

An electric clothes dryer draws 23 A at 220 V.If the clothes put into the dryer have a mass of 7 kg when wet and 4 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) .

A steam turbine at an electric power plant delivers 4,600 kW of power to an electrical generator which converts 85% of this mechanical energy into electrical energy.What is the current delivered by the generator if it delivers at 3,200 V?

A 55-W light bulb is in a socket supplied with 100 V.What is the current in the bulb?

If a 550-W heater carries a current of 3 A,what is the voltage across the ends of the heating element?

If a lamp has resistance of 110 Ω when it operates at 100 W,what is the applied voltage?

The temperature coefficient of resistivity for a "perfect" ohmic material would be:

The heating coil of a hot water heater has a resistance of 25 Ω and operates at 220 V.How long a time is required to raise the temperature of 150kg of water from 25°C to 85°C? (The specific heat for water = 103 cal/kg⋅°C and 1.0 cal = 4.186 J) .

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?

If a 12-V battery,with negligible internal resistance,and an 20-Ω resistor are connected in series,what is the amount of electrical energy transformed to heat per coulomb of charge that flows through the circuit?

If electrical energy costs 4 cents per kWh,what does it cost to heat 210 kg water from 30°C to 65°C? (The specific heat of water = 10³ cal/kg⋅°C and 1.0 cal = 4.186 J. )

An electric clothes dryer draws 23 A at 220 V.If the clothes put into the dryer have a mass of 7 kg when wet and 4 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) .

The heating coil of a hot water heater has a resistance of 25 Ω and operates at 220 V.How long a time is required to raise the temperature of 150kg of water from 25°C to 85°C? (The specific heat for water = 10³ cal/kg⋅°C and 1.0 cal = 4.186 J) .