In the given figure the capacitors 
have a capacitance 4mF each if the capacitor 
has a capacitance 10mF, then effective capacitance between A and B will be
|
(a) 2mF |
(b) 4mF |
(c) 6mF |
(d) 8mF |
(b) 4mF
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In the figure shown there are two semicircles of radii 
and 
in which a current i is flowing. The magnetic induction at the centre O will be
|
(a) |
(b) |
(c) |
(d) |
and 
are the electrical conductivities of Ge and Na respectively. If these substances are heated, then
|
(a) Both |
(b) |
|
(c) |
(d) Both |
Two coils A and B having turns 300 and 600 respectively are placed near each other, on passing a current of 3.0 ampere in A, the flux linked with A is 1.2 
and with B it is 9.0 
. The mutual inductance of the system is
|
(a) 2 × 10–5 henry |
(b) 3 × 10–5 henry |
(c) 4 × 10–5 henry |
(d) 6 × 10–5 henry |
Assertion : An ac generator is based on the phenomenon of self-induction.
Reason : In single coil, we consider self-induction only.
|
(a) If both assertion and reason are true and the reason is the correct explanation of the assertion. |
|
(b) If both assertion and reason are true but reason is not the correct explanation of the assertion. |
|
(c) If assertion is true but reason is false. |
|
(d) If assertion is false but reason is true. |
The coefficient of self inductance of a solenoid is 0.18 mH. If a crode of soft iron of relative permeability 900 is inserted, then the coefficient of self inductance will become nearly
|
(a) 5.4 mH |
(b) 162 mH |
(c) 0.006 mH |
(d) 0.0002 mH |
The approximate ratio of resistances in the forward and reverse bias of the PN-junction diode is
(a) 
|
(b) 
|
(c) 
|
(d) 
|
