A1.60 m cylindrical rod of diameter 0.550 cm is connected to a power supply that maintains a constant potential difference of 17.0 v across its ends, while an ammeter measures the current through it. you observe that at room temperature (20.0 ∘c) the ammeter reads 18.7 a , while at 92.0 ∘c it reads 17.3 a . you can ignore any thermal expansion of the rod.

part a

find the resistivity and for the material of the rod at 20 ∘c.

part b

find the temperature coefficient of resistivity at 20∘c for the material of the rod.

2) an 18-gauge copper wire (diameter 1.02 mm) carries a current with a current density of 1.90×106 a/m2 . copper has 8.5×1028 free electrons per cubic meter.

part a

calculate the current in the wire.

express your answer using two significant figures.

part b

calculate the drift velocity of electrons in the wire.

express your answer using two significant figures.

You have been consulted by the mobile phone company hookup about a new augmented reality product called “brows”. they want to develop an alternative to google glasses, which, you recall, is a proposed new product which plans to superimpose a whole range of wireless google services over the user’s ordinary vision of the world. these appear in little circles and ovals, and let you phone people, take photographs, navigate across cities and inside buildings, find shops and update your social media. brows would do this too, but not be limited to special google services. the user would wear a small cylinder-shaped device designed to fit on top of their existing eyewear (glasses or sunglasses). it would project a reversed image onto the inside of the lenses, the reflection of which would be in focus for the user. instead of voice control, the user would control the device by eye and neck movements, which the device would track. the device would connect via bluetooth to the user’s phone, which would supply most of the computing power and wireless connectivity. hookup also wants to know what existing services would be most in demand, and which would not work well with brows. using your knowledge of augmented reality, wearable technology and interface design, is the project feasible? if not, why not? if feasible, how could the product need to be modified for a better experience?

Explain how the energy of rubber ball is tranforned as it roll down a ramp. give evidence that the energy of the og the ball remains the same at all points on the ramp

How many times did thomas edison mess up the light bulb