{[ promptMessage ]}

Bookmark it

{[ promptMessage ]}

quiz2solns

# quiz2solns - Physics 1B Electricity Magnetism Summer...

This preview shows pages 1–3. Sign up to view the full content.

Physics 1B: Electricity & Magnetism Summer Session I, 2010 Quiz #2, July 8, 2010 This is version A ! 1. At all points on the surface of a spherical volume of radius 0.6 m, there is an electric field of intensity 100 N/C directed radially outward. What is the net charge enclosed within this volume? a. 0.32 nC b. 4.0 nC c. 6.7 nC d. 24.0 nC e. 66.7 nC We can use Gauss’s Law, Φ E = Q encl 0 , but first we need to calculate Φ E , which in this case can be calculated as just EA since the electric field lines are perpendicular to the surface. Φ E = EA = E 4 πr 2 = (100 N/C )(4 π (0 . 6 m ) 2 ) = 452 Nm 2 /C . From Gauss’ Law, Q encl = Φ E ǫ 0 = ( E 4 πr 2 ) ǫ 0 = (100 N/C )(4 π (0 . 6 m ) 2 )(8 . 85 × 10 - 12 C 2 N - 1 m - 2 ) = 4 . 0 × 10 - 9 C = 4.0 nC . 2. When charge Q 1 is placed at point P 1 , the resulting potential at point X is V 1 . Then, when Q 2 is placed at point P 2 , the resulting potential at point X becomes V 2 . What is the potential at point X if charge Q 1 is then removed? The total potential at any point in space is due to the sum of the potentials from each charge. The answer is V 2 – V 1 , as the potential due to only Q 1 (V 1 ) plus the potential due to only Q 2 (V 2 – V 1 ) equals the potential due to both (V 2 ). 1

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
3. Consider a uniform electric field of 500 N/C pointing in the +x direction. You wish to move the nucleus of a single ionized carbon atom (12 protons, 12 neutrons) a distance of 10 cm in the –x direction. How much work do you need to provide?
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}