2. Three point charges are fixed in place at the corners of a trapezoid as shown. The upper side has length 3.0 cm, the base has length 5.0 cm and the height is 3.0 cm. q, =+ 10.0 nC, 3 cm =- 5.0 nC, and 93 =+ 5.0 nC. 92 a. Find the electric field at point P, the lower left corner of the trapezoid. b. Find the electric potential at point P taking the potential at infinity to be zero. 3 cm| -27 = 1. 67 x 10 "kg) 1 cm c. Suppose a proton (m is placed at point P and is released from rest. What will its speed be when it is very far from the arrangement of charges? 1 cm 3 cm

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**Problem 2: Electric Charge Configuration**

Three point charges are fixed in place at the corners of a trapezoid as shown. The upper side has length 3.0 cm, the base has length 5.0 cm, and the height is 3.0 cm. The charges are as follows:

- \( q_1 = +10.0 \, \text{nC} \)
- \( q_2 = -5.0 \, \text{nC} \)
- \( q_3 = +5.0 \, \text{nC} \)

Questions:

a. **Electric Field at Point P**  
   Find the electric field at point P, the lower left corner of the trapezoid.

b. **Electric Potential at Point P**  
   Find the electric potential at point P, taking the potential at infinity to be zero.

c. **Motion of a Proton**  
   Suppose a proton (\( m = 1.67 \times 10^{-27} \, \text{kg} \)) is placed at point P and is released from rest. What will its speed be when it is very far from the arrangement of charges?

**Diagram Explanation:**
- The diagram depicts a trapezoid with point charges at each corner.
- \( q_1 \) and \( q_2 \) are located at the top corners, each 3 cm apart.
- \( q_3 \) is at the bottom right corner, 1 cm from the base's end, making the base 5 cm long.
- Point P is located at the lower left corner of the trapezoid, 1 cm from \( q_1 \). 

This problem requires understanding concepts of electric fields and potentials in the context of a multiple-charge system.
Transcribed Image Text:**Problem 2: Electric Charge Configuration** Three point charges are fixed in place at the corners of a trapezoid as shown. The upper side has length 3.0 cm, the base has length 5.0 cm, and the height is 3.0 cm. The charges are as follows: - \( q_1 = +10.0 \, \text{nC} \) - \( q_2 = -5.0 \, \text{nC} \) - \( q_3 = +5.0 \, \text{nC} \) Questions: a. **Electric Field at Point P** Find the electric field at point P, the lower left corner of the trapezoid. b. **Electric Potential at Point P** Find the electric potential at point P, taking the potential at infinity to be zero. c. **Motion of a Proton** Suppose a proton (\( m = 1.67 \times 10^{-27} \, \text{kg} \)) is placed at point P and is released from rest. What will its speed be when it is very far from the arrangement of charges? **Diagram Explanation:** - The diagram depicts a trapezoid with point charges at each corner. - \( q_1 \) and \( q_2 \) are located at the top corners, each 3 cm apart. - \( q_3 \) is at the bottom right corner, 1 cm from the base's end, making the base 5 cm long. - Point P is located at the lower left corner of the trapezoid, 1 cm from \( q_1 \). This problem requires understanding concepts of electric fields and potentials in the context of a multiple-charge system.
Expert Solution
Step 1

Given:

Length of upper side of the trapezoid =3.0 cm

Length of the base of the trapezoid =5.0 cm

Height of the trapezoid =3.0 cm

q1=10.0 nC,  q2=-5.0 nC  and q3=+5.0 nC

Calculation:

(a) The electric field at point P is calculated as follows.

Let us first of all redraw the given figure in a simple way.

Advanced Physics homework question answer, step 1, image 1

Now let us calculate the distance AP between the charge q1 and point Pwith the help of "Pythagorium theorem".AP=(AQ)2+(PQ)2    =(3)2+(1)2    =10 cm    =3.2 cm    =0.032 mSo the field at "P" due to q1 is E1=14π ε0q1(AP)2   =(9×109)10×10-9(0.032)2   =87890.6VmThe direction of this field is "away" from q1.Now we will calculate at P field due to q3.Now distance CP between q3 and P is 5 cm or 0.05 m.So field at P due to q3 is,E3=14π ε0q3(CP)2    =(9×109)5×10-9(0.05)2    =18000 VmThis field is directed "away" from q3.Now to calculate resultant of E1 and E3 we need to find the value ofAPQ.From APQtan(A)=13A=tan-1(13)         =18.43°Hence, APQ=P=[180°-(90°+18.43°)]                              =71.57°Hence, the resultant of E1 and E3 isE13=E12+E32+2 E1 E3 cos(71.57°)     =(87890.6)2+(18000)2+2×(87890.6)×(18000)×0.316     =95124.13 VmNow we will calculate field due to q2.First we will calculate the distance BP between q2 and point P using "Pythagorium theorem".BP=(BR)2+(PR)2    =(3)2+(4)2    =5 cm    =0.05 m.So, the field due to q2 isE2=14π ε0q2(BP)2    =(9×109)×5×10-9(0.05)2    =18000 VmBut the direction of the field is "towards" q2 as magnitude of q2 is negative.So the resultant electric field at P taking all this contributions isER=E132+E22+2 E13 E2 cos(180°)    =(95124.13)2+(18000)2+2×(95124.13)×(18000)×(-1)    =77124.13 VmSo the magnitude of resultant field at P is 77124.13 Vm This field is directed away from point P.

 

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