NARAYANA IIT ACADEMY JEE MAIN – 2013 - Narayana Group

dV
If displaced by x then Frestoring
A.dP AB V
2
Ax
2 BA x
Frestoring
A.B M x
V0 V0
2
P0
A x
V
0
A P 1 A P
2
MV 2 MV
2 2
0 0
0 0
18. If a piece of metal is heated to temperature and then allowed to cool in a room which is at
temperature 0, the graph between the temperature T of the metal and time t will be closed
to :
T
T
T
T
1.
2. 0
3. 0
4. 0
0 t
0 t
0 t
0 t
Ans. (3)
d 4 4
Sol. As per Stefan’s Law
0 which decrease with t
dt
19. This question has Statement – I and Statement – II. Of the four choices given after the
Statements, choose the one that best describes the two Statements.
Statement – I : Higher the range, greater is the resistance of ammeter.
Statement – II : To increase the range of ammeter, additional shunt needs to be used across
it.
(1) Statement – I is true, Statement – II is true, Statement – II is the correct explanation of
Statement – I
(2) Statement – I is true, Statement – II is true, Statement – II is not the correct explanation
of Statement – I
(3) Statement – I is true, Statement – II is false
(4) Statement – I is false, Statement – II is true
Ans. (4)
Range of the ammeter is given by
R
g
I Ig
1
R
and resistance of the ammeter is given by
R R
gR
R R
g
Hence to have higher range, is the resistance of ammeter should be made smaller.
0
NARAYANA IIT ACADEMY JEE MAIN – 2013