The frequency of an alternator at a given r/min is determined by the _______ . A.number of turns of wire in the armature coil B.number of magnetic poles C.strength of the magnets used D.output voltage
举一反三
- When the number of turns in a solenoid and its length are both doubled, the ratio of the magnitude of the new magnetic field inside to the magnitude of the original magnetic field inside is: A: 0.25 B: 0.50 C: 1 D: 2 E: 4
- The<br/>birth _____ is the number of births compared to the number of the<br/>people. () A: speed B: rate C: frequency D: percentage
- All atoms of a given element have the same __________. A: mass B: number of protons C: number of neutrons D: number of electrons and neutrons E: density
- The larger the number of observations in a numerical data set, the larger the number of class intervals needed for a grouped frequency distribution.
- The number of class intervals in a frequency distribution is usually between ___________.