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JEE Main Physics Class 12 Current Electricity Part 1 Questions
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© examsnet.com
Question : 33
Total: 100
The resistance of an electrical toaster has a temperature dependence given by
R
(
T
)
=
R
0
[
1
+
α
(
T
−
T
0
)
]
in its range of operation. At
T
0
=
300
K
,
R
=
100
Ω
and at
T
=
500
K
,
R
=
120
Ω
. The toaster is connected to a voltage source at 200
V
and its temperature is raised at a constant rate from 300 to
500
K
in
30
s
. The total work done in raising the temperature is :
[Online April 10, 2016]
400
ln
5
6
J
200
ln
2
3
J
300
J
400
ln
1.5
1.3
J
None
Validate
Solution:
Work done in 30s,
W
=
30
∫
0
V
2
R
d
t
or,
W
=
30
∫
0
(
200
)
2
100
(
1
+
α
20
t
3
)
d
t
=
(
200
)
2
100
30
∫
0
d
t
1
+
20
α
3
t
=
400
×
3
20
α
ln
(
1
+
20
α
3
×
30
1
)
=
60
,
000
ln
(
6
5
)
∵
120
=
100
[
1
+
α
(
200
)
]
∴
α
=
1
1000
© examsnet.com
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