# Gltcauses the capacitance to increase

*r” – y’nr*- /-/ Physics2205 Final Exam PRACTICE

University of New Haven Fall,20l7 7-Dec-2017

This exam is open book and open notes and calculators are allowed, but you may not acce\$s the internet. Please no talking during the exam. Total Points: 200

Each Multiple Choice nroblem is worth 6 noints.

,fi. t J 1. A pF.pV is equivalent to a\-1 u a. mT b. pC c. nC e.pN f. nJ Bulb I Bulb 2

2. The circuit in the figure above contains two identical lightbulbs in series with a battery. At first both bulbs glow with equal brightness. When switch S is closed, which of the following occurs to the bulbs?

Bulb 2 Gets brighter

/ Goes out Gets slightly dimmer Gets brighter

“/ Goes out

‘/–L V r& ,> lt

ar^. rkz ,t a{ avttl )rnu –

B (into page)

xxxxx-r}xr)r\* ,^\yx 4. A wire ,””, ;;r) ,*t .U in a time-varying but spatially uniform magnetic field that is

perpendicular to the plane of the loop, as shown above. The induced emf in the loop is given by e :

3. A bar magnet and a wire loop carrying current “1” are arranged as shown above. In which direction, if any, is the force on the current loop due to the magnet? Assume a perfectly circular loop.

a. Toward the magnet 57nra<.?t\t,tle-b. Away from the magnet lvD. Away rom Tne magnet f I eer{eo(l-t tyll^rrc. Toward the top of the page r^ L { r – ‘ ‘

d. Toward the bottom of the page \ -(on.. r s ovhual <4-.rnere is no force on the current loop

/ po,- ar^. rkz

b&tr/2, where b is a constanglhe time varying magnetic field could be given by

(x) !utr”’ @:u,-”.’ G) !tt”’ (o) ?u.qt”’

blil -”

“! r,l r-t’ = A #

(n) ? u”’

?

E 4t

Bulb I -.- a. Goes out

,r”{a}>cets brighter .” c. Get brighter d. Gets slightly dimmer e. Nothing

Se< {^btz Z<t.\ 5. The capacitance of a pure water-filled parallel-plate capacitor with plate area .024nf and separation

0.030-mm is

@ro,r b. 62tlF c. 27 1tF d. 26mF e. 7.0 F

==

k z”/T (g o.’t\ ( s.8s r to-‘-\ (‘o>v)

?*t o -J

= 5-t ,rf,? F

6. A +50 pC charge moves vertically upward at 100 m/s. Which magnetic field will produce a northward magnetic force of 10 mN?

a. 5.0 T, South b. 12.T,North c. 2.5 T, East

ius of curvature of an electron moving at2xl0s m/s in a 400 T uniform magnetic field is .8 nm (q.t4 o-rr)(z*ro t) _t

= 2.6tto[L= (i.e*t”-r{) /voo)

system. What effect does this have on the capacitance?

Gltcauses the capacitance to increase. It causes the capacitance to decrease. None; the capacitance does not change. Nothing can be said about the effect without knowing the dielectric constant of the plastic. Nothing can be said about the effect without knowing the thickness of the sheet.

f=4Y8r,”.0 ^ I.ol l.Ie tu; *- /;ffi-) –

I , ?’6

_(L

40 nm 540 mm 8.3 cm 2l cm

n>Y.p

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(Q 8&9) A capacitor is constructed of two identical conducting plates parallel to each other and separated by a distance d. The capacitor is charged to a potential difference of Voby a battery, which is then disconnected.