Part 1 Nerve cells transmit electric signals through their long tubular axons. T

Question

Part 1

Nerve cells transmit electric signals through their long tubular axons. These signals propagate due to a sudden rush of Na+ ions, each with charge +e, into the axon. Measurements have revealed that typically about 5.4×1011 Na+ ions enter each meter of the axon during a time of 13 ms .

What is the current during this inflow of charge in a meter of axon?

Express your answer using two significant figures.

I = ___ A .... ( MY WRONG ANSWERS: 8.96, 6.89, 6.89 * 10^-6 )

Part 2

A refrigerator draws 3.8 A of current while operating on a 120 V power line. If the refrigerator runs 50 % of the time and electric power costs $0.12 per kWh, how much does it cost to run this refrigerator for a 30-day month?

Express your answer using two significant figures.

Cost = ____ $

Part 3 , Multiple Choice :

A resistor R and another resistor 2.00 R are connected in parallel across a battery.

If heat is produced at a rate of 16.0 W in R, in 2.00 R it is produced at a rate of

8.00 W .

8.00 W .

Explanation / Answer

1) current =charge/time =1.6 x 10-19 x 5.4 x 1011/13 x 10-3 =6.64 micro A

2)power =3.8 x 120 =0.456kW

for 30 days only 50% time

so for 1hr =$0.12

cost =0.12 x 15 x24 x 0.456 =$19.69

3)V2/R =16 given

V=4sqrt(R)

in 2R heat =V2/2R =16/2 =8watt

Related Questions

Navigate

• Browse (All)
• Browse P
• Subjects