Moving Charges and Magnetism - Online Test
Q1. For measuring μA current the galvanometer is
Answer : Option C
Explaination / Solution:
For measurement of current of any magnitude, the galvanometer is always connected in series. This is to ensure that the entire current flows through the galvanometer. If the galvanometer were connected in parallel, the current branches out and only a part of the current will flow through it.
Q2. Shunt resistance is added to the galvanometer
Answer : Option C
Explaination / Solution:
A shunt resistance of magnitude less than that of the galvanometer is added in parallel to the galvanometer to convert it into an ammeter. The equivalent resistance of a parallel combination is always less than the least value of the resistances in parallel. Ammeters are connected in series to the circuit to allow the entire current of the circuit to pass through them. Its resistance has to be very less- almost negligible, so that it does add on to the resistance in the circuit, thereby changing the current.
Q3. A Current carrying wire produces in its neighbourhood
Answer : Option D
Explaination / Solution:
Static charges produce only an electric field. Moving charges produce a magnetic field in addition to their electric fields.
Q4. The magnetic induction in air at point 1 cm away from a long wire that carries a current of 1 A, will be
Answer : Option D
Explaination / Solution:
B=μ0I2πr=4π×10−7×12π×1×10−2=2×10−5T
Q5. A long straight wire carries an electric current of 2 A. The magnetic induction at a perpendicular distance of 5 m from the wire is
()
Answer : Option B
Explaination / Solution:
Q6. The magnetic field due to very long wire carrying current varies according to
Answer : Option C
Explaination / Solution:
The magnetic field at a point, which is at a distance r, from a very long wire carrying current is
Q7. What should be the current in a circular coil of radius 5 cm to annul BH=5×10−5 T at the center?
Answer : Option C
Explaination / Solution:
The magnetic field produced by the coil at the centre should be equal and opposite to the The field at the centre of a circular coil .The current needed to produce a field equal to
Q8. The magnetic field in a circular loop of diameter 0.1 m carrying a current of 1 A is
Answer : Option C
Explaination / Solution:
Q9.
Two protons move parallel to each other with equal speeds 3 x 105 ms-1. The ratio of magnetic and electric force between them is
Answer : Option B
Explaination / Solution:
The approximate ratio of the forces is equal to the ratio of their constants,and
Q10. A particle having charge 100 times that of an electron is revolving in a circular path of radius 0.8 m with one rotation per second. Magnetic field produced at the centre of the circular path is
Answer : Option C
Explaination / Solution:
A charge moving in a circular path is equivalent to a current Since the particle has charge 100 times e and it makes 1 revolution per second,q=100e and T=1s.
The magnetic field at the centre
The magnetic field at the centre
