CBSE physics
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Define capacitor reactance. Write its S.I. units.
The resistance offered by the capacitor when connected to an electrical circuit is known as capacitive reactance.
It is given by,
where, 
is the angular frequency of the source, and
C, is the capacitance of the capacitor.
SI Unit is ohm.
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What is the electric flux through a cube of side 1 cm which encloses an electric dipole?
Given, cube encloses an electric dipole.
So, the total charge enclosed by the cube is zero.
That is, Q= 0.
Now, using the formula for electric flux as per the Gauss’s law of electrostatics, we have
Graph showing the variation of current versus voltage for a material GaAs is shown in the figure. Identify the region of
i) negative resistance
ii) where Ohm’s law is obeyed.
i) The region of negative resistance is DE because, the slope is negative for this part of curve.
ii) BC is the part of the curve where Ohm’s law is obeyed because here, current is varying linearly with with the voltage. This gives us direct proportionality between current and voltage.
Use Kirchhoff’s rules to obtain conditions for the balance condition in a Wheatstone bridge.
A Wheatstone bridge arrangement is shown as below: 
Using Kirchoff’s second law to the loop ABDA, we get 
Applying Kirchoff’s law to loop BCDB, we get
When the bridge is balanced, 
Then, the equations can be written as,
... (1) 
... (2)
On dividing equation (1) by (2), we get
, which is the balanced condition of a Wheatstone bridge.
Name the parts of the electromagnetic spectrum which is
(a) suitable for radar systems used in aircraft navigation.
(b) used to treat muscular strain.
(c) used as a diagnostic tool in medicine.
Write in brief, how these waves can be produced.
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Mock Test Series
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