Homework #6 Problem #4 Two parallel circular disks are separated by a distance o

Question

Homework #6 Problem #4 Two parallel circular disks are separated by a distance of 1.0 mm. The diameter of each disk is 2.0 cm. One of the disks carries a net charge of +10 nC and the other has a charge of -10 nC. (a) What is the electric field strength between the disks? (b) A proton is shot from the negative disk toward the positive disk. The electric field slow down the proton as it travels across the gap. What launch speed must the proton have to just barely reach the positive disk before stopping and turning around? Note that the mass of a proton is m,-1.67 × 10-27 kg , and its charge is 8p = +e +1.602×10-19 C

Explanation / Answer

(a)

The electric field between the plates is

E = /o...

where = area charge distribution = 10X10^-9/(*(0.010m)^2) = 3.183x10^-5C/m^2

and o = 8.854x10^-12C^2/N-m^2

So

E = 3.183x10^-5/8.854x10^-12

= 3.60 x 10^6 N/C

(b)

Using conservation of energy we solve the second part

(K + U) b = (K + U)t...

Here Ut - Ub = q*(Vt - Vb)...

and Vt - Vb = E*d = 3.60x10^6V/m*1.0x10^-3m = 3595V

Since Kt = 0 we have Kb = q*E*d = 1.602x10^-19C*3595 = 5.75919 x 10^-16J

So 1/2*m*v^2 = 5.75919x10^-16J

Therefore v = sqrt(2*5.75919x10^-16J/m)

= sqrt(2*5.75918x10^-16J/1.67x10^-27kg)

= 8.30 x 10^5 m/s

Related Questions

Navigate

• Browse (All)
• Browse H
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.