Science And technology

  1. For which of the following is magnetic susceptibility negative? Paramagnetic and Ferromagnetic materials Paramagnetic Materials only Ferromagnetic Materials only Diamagnetic Materials Answer:  (d) Diamagnetic Materials 2. The Hysteresis loops for two magnetic materials A and B are given below: These materials are used to make magnets for transformer core, electric generators and electromagnet core. Which of the following is true about the given magnets? A for transformers and B for electric generators A for electric generators and transformers B for electromagnets and generators A for electromagnets and B for electric generators Answer:  (c) B for electromagnets and generators 3. Which of the following is the unit of magnetic flux density? Weber/meter 2 Tesla Newton/ampere-metre All of the above Answer:  Tesla 4. The magnetism of a magnet is due to earth cosmic rays due to pressure of big magnet inside the earth spin motion of electrons Answer:  (d) spin mo...

  1. What is the frequency of the AC Mains in India? 60 Hz 50 Hz 40 Hz 30 Hz Answer:  (b)   50 Hz Explanation:  The frequency of the AC Mains in India is 50 Hz. 2. An alternating current can be produced by Choke Coil Dynamo Electric Motor Transformer Answer:  (b) Dynamo Explanation:  An alternating current can be produced by a dynamo. 3. Which of the following can measure an alternating current? Voltmeter Ammeter Suspended coil galvanometer Moving coil galvanometer Answer:  (b) Ammeter Explanation:  Ammeter can measure an alternating current. 4. Which of the following circuits exhibits maximum power dissipation? Pure Inductive Circuit Pure Capacitive Circuit Pure Resistive Circuit None of the above Answer:  (c) Pure Resistive Circuit Explanation:  A pure resistive circuit exhibits maximum power dissipation. 5. What happens to the inductive reactance when the frequency of the AC supply is increased? Increases Decreases Remains the same De...

  Work is something that is accomplished by the action of a  force . The measure of transfer of energy occurs when an object is moved by a distance due to an external force applied in the direction of the  displacement . If we apply a constant force, then the work can be calculated by multiplying the distance covered by the component and the force which is acting along the path. To express this mathematically, work  done W  is equal to the force ex erted f  times the distance covered  d , or  W = fd.  The time rate at which the work is being done or energy is delivered is called  power , which can be expressed as the amount of work done  W,  or energy transferred, against the time interval  t  or  W / t . The Units of power can be expressed as work (or energy) per unit time, foot-pounds per minute, joules per second (or watts), and ergs per second. Power can also be expressed as the product of the force applied t...