NTA Abhyas 2020
- Exam
- NTA Abhyas
- Year
- 2020
- Subject
- Physics
- Chapter
- Magnetic Properties of Matter
NTA Abhyas 2020 · Physics · Magnetic Properties of Matter
A magnetic needle free to rotate in a horizontal plane is placed at...
A magnetic needle free to rotate in a horizontal plane is placed at the centre of a circular current-carrying coil whose axis is perpendicular to the magnetic meridian at that place. It is also known that the magnetic declination at this place is zero and in this condition, the magnetic needle is pointing towards the north-west. Now, if we reverse the direction of current in the coil, then the magnetic needle will
Options
- Apoint north-west
- Bpoint north-east
- Cpoint south-east
- Dpoint south-west
Correct answer
B. point north-east
Step-by-step solution
If there is no current in the coil, then the needle would point north but due to the magnetic field of the coil, it is pointing north-west. This means the magnetic field due to the coil is towards west and it is equal to the horizontal component of earth's magnetic field. So when we reverse the direction of current the magnetic field due to the coil will be towards east and the magnetic needle will point north-east.