1. A 33-? resistor has a voltage difference of 8 V across its leads. (a) What is

Question

1. A 33-? resistor has a voltage difference of 8 V across its leads.

(a) What is the current through the resistor?

________ A

(b) What is the power being dissipated in this resistor?

_________ W

________________________________________________________________

2. A toaster draws a current of 7 A when it is connected to a 220-V ac line.

(a) What is the power consumption of this toaster?

________  W

(b) What is the resistance of the heating element in the toaster?

_____________ ?

________________________________________________________________

A 33-? resistor has a voltage difference of 8 V across its leads. What is the current through the resistor? ________ A What is the power being dissipated in this resistor? _________ W A toaster draws a current of 7 A when it is connected to a 220-V ac line. What is the power consumption of this toaster? ________ WWhat is the resistance of the heating element in the toaster? _____________ ? In the circuit shown below, the r = 2-? resistance is the internal resistance of the battery and can be considered to be in series, as shown, with the battery and the R = 7-? load. (Let epsilon = 5 V What is the current flowing through the 7-? resistor? ______________ A What is the voltage difference across the 7-? resistor? ______________ V Three resistors are connected to a 8-V battery as shown. The internal resistance of the battery is negligible. What is the current through the 15-? resistance? ______________A Does this same current flow through the 25-? resistance? Yes No What is the voltage difference across the 20-? resistance? _______________V Three identical resistances, each 10 ?, are connected in parallel with one another as shown below. The combination is connected to a 18-V battery whose internal resistance is negligible. What is the equivalent resistance of this parallel combination? ____________ ?What is the total current through the combination? ____________ A How much current flows through each resistor in the combination? ___________ A

Explanation / Answer

1).

V = I*R (V=voltage, I = current, R = resistance)

power = (V*V)/R = I*V

a) current,I = V/R = 8/33 = 0.24

b) power = 8*8/33 = 1.94

2). power = (V*V)/R = I*V

a) => power = 7*220 = 1540 W (this is avg power in case of AC)

b) => R = V/I = 220/7 = 31.42 ohm

3). total resistance = R + r = 7+2 = 9 ohm

total current = V/R = 5/9 = 0.56 A

and current in series is same

a). => current flowing through the 7 ohm resistor = 0.56A

b). Voltage diff in 7 ohm register = I*R = 0.56*7 = 3.89 V

4). connected in series so current will be same

total Resistance = 15 + 20+ 25 = 60

current in circuit = 8/60 = 0.133 I

a). the current through the 15 ohm resistance = 0.133 I

b). Yes.. since its a series connection

c) voltage difference across the 20 ohm resistance = I*R = 0.133 * 20

= 2.66 V

5) this is parallel connection..

here voltage difference will be same but current will be different

since all the resistance are of 10 ohm current will divide equally

totol resistance, R in parallel can be calculated as..

1/R = 1/(R1) + 1/(R2) 1/(R3) +... and so on..

where R1,R2,R3.. are resistances connected in parallel

so total resistance of this circuit =>

1/R = 1/10 + 1/10 + 1/10

=> 1/R = 3/10

=> R = 10/3 = 3.33

a). equvivalent resistance = 3.33 ohm

b). total current = V/R = 18/3.33 = 5.4 A

c). current in each resistor = (total current)/3

=> 5.4/3 = 1.8 A

NOTE : total current is not same in parallel when registers are not same

you will have to calculate it using I=V/R (V remains same in parallel connection)

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