Answer:
The answers and workings is in the Explanation section
Explanation:
<em>In a simple circuit a 6-volt dry cell pushes charge through a single lamp which has a resistance of 3 Ω. According to Ohms law the current through the circuit is _____________ Amps.
</em>
According to Ohm’s law V =I*R
Where V = Voltage, I = Current and R = Resistance
I = V/R =6/3 =2 Amps of current
Answer = 2 Amps
<em> If a second identical lamp is connected in series, the 6-volt battery must push a charge through a total resistance of ________ Ω</em>. <em>The current in the circuit is then __________ Amps.
</em>
Since the second lamp is connected in series with the first, the total resistance will R₂ = 3 + 3 = 6Ω
2 resistance in series R₂ = 6Ω
The current in the circuit with the two lamps connected in series is I₂ =V/R₂ =6/6 = 1 Amps
The current is 1 Amps
Answer = 6Ω and 1 Amps
<em>If a third identical lamp is connected in series, the total resistance is now _________Ω. The current through all three lamps in series is now _________ Amps. </em>
Since the third lamp is connected in series with the first and second, the total resistance will R₃ = 3 + 3 + 3 = 9Ω
total resistance of the 3 lamps R₃ = 9Ω
The current in the circuit with the three lamps connected in series is
I =V/R₃ =6/9 = 0.67 Amps
The current through the 3 lamps I₃ = 0.67 Amps
Answer = 9Ω and 0.67 Amps
<em>The current through each individual lamp is __________ Amps. </em>
Since all 3 lamps are connected in series, the same current will flow through each of the 3 lamps, and that current is I₃
The current through each individual lamp is 0.67 Amp
Answer = 0.67 Amp
<em>What is the power when a voltage of 120 volts drives a current of 3 amps through a device? </em>
The formula for power P = I*V =120*3 = 360 Watts
power P = 360 Watts
Answer = 360 Watts
<em>What is the current when a 90-W light bulb is connected to 120 V?
</em>
From P =I*V, make I the subject of the formula, I = P/V =90/120 = 0.75
Current= 0.75 Amps
Answer = 0.75 Amps
<em>How much current does a 75-W light bulb draw when connected to 120 V?</em>
Current I =P/V = 75/120 = 0.625 Amps.
Answer = 0.625 Amps
<em>If part of an electric circuit dissipates energy at 6 W when it draws a current of 3 A, what voltage is impressed across it?
</em>
Voltage V =P/I =6/3 =2 Volts
Answer = 2 Volts
<em> If a 60 W light bulb at 120 V is left on in your house to prevent burglary, and the power company charges 10 cents per kilowatt-hour, how much will it cost to leave the bulb on for 30 days? Show your work.
</em>
24 hours make 1 day, so the number of hours the bulb was left on = 24 *30 = 720 hours
The power rating of the bulb is 60W = 60/1000 = 0.06 KiloWatt
Total power consumed in kilowatt-hour = 0.06 * 720 = 43.2 kilowatt-hour
Cost for 30 days = 0.1*43.2 = $4.32 ( note that 10 Cents = $0.1)
Answer = $4.32
