A light bulb is rated at 6.40 W when operated at 66 V and the tungsten filament becomes hot and glowing at 140 ∘C. What is its resistance (in ohms) at 20 ∘C if the tungsten has a temperature coefficient of resistivity α=4.5×10−3 ∘C−1.

1. a camcorder has a power rating of 19 watts. if the output voltage from its battery is 7 volts, what current does it use?answer units 2. a 1.5m wire carries a 6 a current when a potential difference of 57 v is applied. what is the resistance of the wire? your

Glass has a hardness that is in the middle of the hardness scale. what is the hardness of glass?

Uranium has two naturally occurring isotopes. 238u has a natural abundance of 99.3% and 235u has an abundance of 0.7%. it is the rarer 235u that is needed for nuclear reactors. the isotopes are separated by forming uranium hexafluoride uf6, which is a gas, then allowing it to diffuse through a series of porous membranes. 235uf6 has a slightly larger rms speed than 238uf6 and diffuses slightly faster. many repetitions of this procedure gradually separate the two isotopes. what is the ratio of the rms speed of 235uf6 to that of 238uf6? express your answer to five significant figures.