An electrical appliance is rated 200 v100 w. What is the resistance of the appliance? Five such appliances run simultaneously for 4 hours. What is the energy consumed? Calculate the cost of running these appliances if the per unit cost is rs 4.60.
Answers
Power =
Given: V = 200V, P = 100W
(note that these are RMS values, however the formula is valid, as long as both V and P are RMS)
So, resistance = V²/P = (200)²/100 ohms = 400 ohms.
In 4 hours, the energy consumed by one appliance = power * time = 100W * 4hr = 400W-hr = 0.4kWh.
Now, for five appliances, total energy consumed = 0.4 * 5 kWh = 2 kWh.
(note: kWh is the default commercial unit of electrical energy)
For 2 units of energy, the total cost shall amount to be: 2 * 4.6 Rs. = 9.2 Rs.
Answer:
Find solutions
CameraIcon
SearchIcon
MyQuestionIcon
Home
>
A bulb is rated at 200 V 100 W. what is it's resistance? Five such bulbs burn for 4 hours. What is the electrical energy consumed? Calculate the cost if the rate is 4.60ruppes per unit.
Question
A bulb is rated at 200V-100W. What is it's resistance? Five such bulbs burn for 4 hours. What is the electrical energy consumed? Calculate the cost if the rate is 4.60 ruppes per unit.
Solution
Here, Power (P) = 100 watts = (100/1000)kilowatts
=0.1 kw
Voltage (V) = 200 Volts
Time (t) = 4 hrs.
We know that
Power = P =
V
2
R
⇒
R
=
V
2
P
⇒
R
=
200
2
100
=
40000
100
=
400
Ω
A
l
s
o
,
E
=
P
×
t
E
=
100
×
4
×
60
×
60
=
1.44
×
10
6
J
.: Energy consumed by each bulbs =
1.44
×
10
6
3.6
×
10
6
= 0.4 KWh.
total energy in units =
5
×
0.4
= 2 units
Since the cost of 1 unit of electricity = Rs. 4.60
Therefore, Cost of 2 units of electricity = 4.60 x 2 = Rs 9.20
Explanation:
Find solutions
CameraIcon
SearchIcon
MyQuestionIcon
Home
>
A bulb is rated at 200 V 100 W. what is it's resistance? Five such bulbs burn for 4 hours. What is the electrical energy consumed? Calculate the cost if the rate is 4.60ruppes per unit.
Question
A bulb is rated at 200V-100W. What is it's resistance? Five such bulbs burn for 4 hours. What is the electrical energy consumed? Calculate the cost if the rate is 4.60 ruppes per unit.
Solution
Here, Power (P) = 100 watts = (100/1000)kilowatts
=0.1 kw
Voltage (V) = 200 Volts
Time (t) = 4 hrs.
We know that
Power = P =
V
2
R
⇒
R
=
V
2
P
⇒
R
=
200
2
100
=
40000
100
=
400
Ω
A
l
s
o
,
E
=
P
×
t
E
=
100
×
4
×
60
×
60
=
1.44
×
10
6
J
.: Energy consumed by each bulbs =
1.44
×
10
6
3.6
×
10
6
= 0.4 KWh.
total energy in units =
5
×
0.4
= 2 units
Since the cost of 1 unit of electricity = Rs. 4.60
Therefore, Cost of 2 units of electricity = 4.60 x 2 = Rs 9.20