* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download 1. A magnetic compass needle is placed in the plane... as shown in Figure. In which plane should a straight... X- Guess Questions solved SA-1: Magnetic effects of currents
Friction-plate electromagnetic couplings wikipedia , lookup
Maxwell's equations wikipedia , lookup
Earthing system wikipedia , lookup
History of electromagnetic theory wikipedia , lookup
History of electrochemistry wikipedia , lookup
Neutron magnetic moment wikipedia , lookup
Magnetic nanoparticles wikipedia , lookup
Magnetic monopole wikipedia , lookup
Alternating current wikipedia , lookup
Magnetic field wikipedia , lookup
Electricity wikipedia , lookup
Electromagnetism wikipedia , lookup
Lorentz force wikipedia , lookup
Electromotive force wikipedia , lookup
Hall effect wikipedia , lookup
Earth's magnetic field wikipedia , lookup
Magnetic core wikipedia , lookup
Electric current wikipedia , lookup
Multiferroics wikipedia , lookup
Skin effect wikipedia , lookup
Electric machine wikipedia , lookup
Superconducting magnet wikipedia , lookup
Faraday paradox wikipedia , lookup
Force between magnets wikipedia , lookup
Magnetochemistry wikipedia , lookup
Magnetoreception wikipedia , lookup
Superconductivity wikipedia , lookup
Magnetohydrodynamics wikipedia , lookup
Scanning SQUID microscope wikipedia , lookup
Eddy current wikipedia , lookup
X- Guess Questions solved SA-1: Magnetic effects of currents 1. A magnetic compass needle is placed in the plane of paper near point A as shown in Figure. In which plane should a straight current carrying conductor be placed so that it passes through A and there is no change in the deflection of the compass? Under what condition is the deflection maximum and why? Answer: In the plane of the paper itself. The axis of the compass is vertical and the field due to the conductor is also vertical. It could result in a dip of compass needle which is not possible in this case (dips result only if axis of compass is horizontal). The deflection is maximum when the conductor through A is perpendicular to the plane of paper and the field due to it is maximum inthe plane of the paper. 2. Under what conditions permanent electromagnet is obtained if a current carrying solenoid is used? Support your answer with the help of a labeled circuit diagram. Answer: (i) The current through the solenoid should be direct current. (ii) The rod inside is made of a magnetic material such as steel. 3. A magnetic compass shows a deflection when placed near a current carrying wire. How will the deflection of the compass get affected if the current in the wire is increased? Support your answer with a reason. Answer: The deflection increases. The strength of magnetic field is directly proportional to the magnitude of current passing through the straight conductor. 4. Meena draws magnetic field lines of field close to the axis of a current carrying circular loop. As she moves away from the centre of the circular loop she observes that the lines keep on diverging. How will you explain her observation Answer: Strength of the magnetic field falls as distance increases. This is I indicated by the decrease in degree of closeness of the lines of field. Download: www.jsuniltutorial.weebly.com Page 1 5. Name four appliances wherein an electric motor, a rotating device that converts electrical energy to mechanical energy, is used as an important component. In what respect motors are different from generators? Answer: Electric fans, mixers, washing machines, computer drives, etc. Motors convert electrical energy into mechanical energy whereas generators convert mechanical energy into electrical energy. 6. What is the difference between a direct current and an alternating current? How many times does AC used in India change direction in one second? Answer: Direct current always flows in one direction but the alternating current reverses its direction periodically. The frequency of AC in India is 50 Hz and in each cycle it alters direction twice. Therefore AC changes direction 2 × 50 = 100 times in one second. Long Answer Questions 7. Why does a magnetic compass needle pointing North and South in the absence of a nearby magnet get deflected when a bar magnet or a current carrying loop is brought near it. Describe some salient features of magnetic lines of field concept. Answer: Current carrying loops behave like bar magnets and both have their associated lines of field. This modifies the already existing earth’s magnetic field and a deflection results. Magnetic field has both direction and magnitude. Magnetic field lines emerge from N-pole and enter Spole. The magnetic field strength is represented diagrammatically by the degree of closeness of the field lines. Field lines cannot cross each other as two values of net field at a single point cannot exist. Only one value, a unique net value, can exist. If in a given region, lines of field are shown to be parallel and equispaced, the field is understood to be uniform. 8. With the help of a labelled circuit diagram illustrate the pattern of field lines of the magnetic field around a current carrying straight long conducting wire. How is the right hand thumb rule useful to find direction of magnetic field associated with a current carrying conductor? Answer: Right hand thumb rule states that if a current carrying straight conductor is supposedly held in the right hand with the thumb pointing Download: www.jsuniltutorial.weebly.com Page 2 towards the direction of current, then the fingers will wrap around the conductor in the direction of the field lines of the magnetic field. 9. Explain the phenomenon of electromagnetic induction. Describe an experiment to show that a current is set up in a closed loop when an external magnetic field passing through the loop increases or decreases. Answer: The process by which a changing magnetic field in a conductor induces a current in another conductor is called electromagnetic induction. Explain the working of the set up with the help of the diagram. 10. Draw an appropriate schematic diagram showing common domestic circuits and discuss the importance of fuse. Why is it that a burnt out fuse should be replaced by another fuse of identical rating? Answer: A fuse in a circuit prevents damage to the appliances and the circuit due to overloading. Otherwise the appliances or the circuit may get damaged. Download: www.jsuniltutorial.weebly.com Page 3