A net charge of 47 mC passes through the cross-sectional area of a wire in 19.0 s.
(a) What is the current in the wire?
1 A
(b) How many electrons pass the cross-sectional area in 1.0 min?
2 electrons
I =q/t = 47•10^-3/19 =2.47•10^-3 A .
Q =I•t1 = 2.47•10^-3 • 60 = 0.148 C.
N =Q/e = 0.148/1.6•10^-19= 9.3•10^17
both of these are wrong?
To find the current in the wire, we can use the formula:
Current (I) = Charge (Q) / Time (t)
(a) Given:
Charge (Q) = 47 mC
Time (t) = 19.0 s
First, convert the charge from milliCoulombs (mC) to Coulombs (C):
47 mC = 47 × 10^(-3) C = 0.047 C
Using the formula, substitute the values:
Current (I) = 0.047 C / 19.0 s
Current (I) ≈ 0.0025 A
Therefore, the current in the wire is approximately 0.0025 Amperes or 2.5 milliamperes.
(b) To find the number of electrons passing through the cross-sectional area in 1.0 minute, we need to use the relationship between charge and the charge of an electron.
Charge (Q) = Number of electrons (n) × Charge of an electron (e)
Rearranging the formula, we get:
Number of electrons (n) = Charge (Q) / Charge of an electron (e)
Given:
Charge (Q) = 47 mC
Time (t) = 1.0 min
First, convert the charge from milliCoulombs (mC) to Coulombs (C):
47 mC = 47 × 10^(-3) C = 0.047 C
Next, find the charge of an electron (e):
The charge of an electron is approximately -1.602 × 10^(-19) C (negative because electrons have a negative charge).
Using the formula, substitute the values:
Number of electrons (n) = 0.047 C / (-1.602 × 10^(-19) C)
Calculating the result gives us:
Number of electrons (n) ≈ -2.937 × 10^(17)
Note: The negative sign in the result indicates that the electrons have a negative charge.
Therefore, approximately 2.937 × 10^(17) electrons pass through the cross-sectional area in 1.0 minute.