Question

5) The force between two parallel wires carrying electric current is repulsive when: A) The magnitude of the current of both wires are the same. B) The direction of current in wires are opposite C) One of the wires is carrying no current D) The direction of the currents in wires are the same. E) Wires carrying different current values. 6) Ampere's law provides a convenient way of calculating: A) Electric field due to current distribution. B) Magnetic field due to distribution of electric current. C) The force between a numbers of wires carrying current. D) Magnetic force on a wire carrying current. E) Magnetic field due to charge distribution. 7) Which one of the following is not correct about mass spectrometer? A) Particles regardless of mass and charge enter to the second magnetic field with same velocity. B) Charges with same charge value can enter into the second magnetic field. C) For two charges with same charge value, the radius of the circular motion is smaller for particle with less mass. D) For two charges with same charge value, the radius of the circular motion is larger for particle with less mass. E) Mass spectrometer is capable of measuring a number of masses at the same time. 8) A laser beam has a circular cross section with radius of r and power P. If we focus this laser beam with the same power P to a smaller radius of r/2, the intensity of the laser beam becomes: A) half B) twice C) one-quarter D) four times E) eight times