Test+FyBCh20 21NVC06+Magnetic+Induction+&+AC+Circuits

8/3/2019 Test+FyBCh20 21NVC06+Magnetic+Induction+&+AC+Circuits

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Test FyBCh20-21, 24 NVC06 magnetic Induction & AC circuits NV-College

Physics B: FyBNVC06Electromagnetism and Induction, Spectroscopy

Instructions:

Time: 12:35-15:25

The Test Warning! There are more than one version of the test.

At the end of each problem a maximum point which one may get for a correct solution

of the problem is given. (2/3/¤) means 2 G points, 3 VG points and an MVG ¤ quality.

Tools Approved formula sheets, ruler, and graphic calculator. You may use one page of a

personalized formula sheet which has your name on it. This should be submitted along

with the test.

Grade limits: Maximum score 67, where 36 of them are VG points and 2 ¤ (MVG)

Lower limits for examination grade

Pass (G): 22 points

Pass with distinction (VG): 44 points of which at least 12 VG-points

Pass with special distinction (MVG): 50 points of which at least 24 VG-points and you

must show several Pass with Special Distinction qualities in at least three of ¤-marked

qualities.

Problems number 8 and 9 are heavily graded and are of greatest importance for both

VG and MVG. You may choose to solve these problems before solving the others.

1a 1b 1c 1d 1e 1f 1g 2a 2b 3 4 Sum

G 1 1 1 1 1 1 1 1 1 2 1 12

VG 3 2 2 1 1 2 11

GVG

5a 5b 5c 5d 6a 6b 6c 7 8 9a 9b Sum Total

G 2 1 1 1 2 2 2 1 2 1 2 17 29

VG 2 1 1 1 1 3 3 4 4 1 4 25 36

MVG ¤ ¤ 2 2

G

VG

MVG

© [email protected] ☺Free to use for educational purposes. Not for sale. 1/7




Part I: Answer part I on this paper Part I: Answer part I on this paper

1. In the figure below a proton is projected horizontally at sm / into the region

between two parallel charged plates which are

100.55

×

mm0.10 apart. The potential difference

between the plates is V .600 .

−−−−−−−−−−−−

++++++++++++

pmm0.10

cm0.2

sm /100.5 5×

a) Draw the electric filed lines as clear as possible on the figure. [1/0]

b) In which direction will the proton be deflected? [1/0]

i) Toward the bottom of the paper.

ii) Toward the top of the page.

iii) Into the page.

iv) Out of the page.

Answer: Alternative:





c) What is the magnitude of the electric field? [1/0]c) What is the magnitude of the electric field? [1/0]

i) i) mV /0.60

ii) mmV /0.60

iii) mV /0.60

iv) mkV /0.60

v) m MV /0.60

Solution: Answer: Alternative

d) The magnitude of the electric force on the proton is: [1/0]

i) N .106.9 14−×

ii) N .106.1 19−×

iii) N 15106.9 −×

iv) N 15106.2 −×


e) If the plates are cm0.2 long, and the proton is ejected horizontally into the plates,

exactly in the middle of the plates, i.e. mm0.5 from each plate, in what angle

will the proton leave the plates? [1/0]

i) at °= 25θ with x-axis. Downward.ii) at °= 13θ with x-axis. Downward.

iii) at °= 3.1θ with x-axis. Downward.

iv) at °= 25θ with x-axis. Upward.

v) It will not leave the plates. It will hit the plate below.

vi) at °=θ with x-axis. (fill the space, if none of above corresponds to your

calculations. Indicate if it is DOWNWARDS or UPWARDS.)

Draw the required figures, and show the details of your calculations: [0/3]






f) If we would like the ejected proton leaving the plates area horizontally, we may

turn on a magnetic field in the region. The direction of such a magnetic field is:

[1/0]

i) perpendicular to the original direction of the proton, into the paper.

ii) perpendicular to the original direction of the proton, out of the paper.

iii) perpendicular to the original direction of the proton, vertically upward.iv) perpendicular to the original direction of the proton, vertically downward

v) horizontal to the left in the original direction of the proton’s motion.

vi) horizontal to the right in the opposite direction of the proton’s motion.

Answer: Alternative __________________

Draw necessary figures and explain your reasoning. [0/2]


g) What is the magnitude of such a magnetic field: [1/0]

i) T B 12=

ii) mT B 12=

iii) T B 12.0=

iv) kT B 12=

v) MT B 12=

vi) None of above. It is :__________

Answer: Alternative __________________

Show the details of your calculations: [0/2]





2. Show clearly the direction of the induced current in the circular loops below due to the

current shown? Why? Explain and Draw it on the figure:

2. Show clearly the direction of the induced current in the circular loops below due to the

current shown? Why? Explain and Draw it on the figure:

i. Explanation: [1/1]i. Explanation: [1/1]

decreasesI

ii. Explanation: [1/1]ii. Explanation: [1/1]

increasesI

3. The magnetic flux through a coil of wire containing3. The magnetic flux through a coil of wire containing 100 loops change from Wb56 to

Wb54− in s20.0 . What is the emf induced in the coil? [2/0]

Solution:





CD

AB

E

F

18 cm

Part II

4. An electron and an alpha particle have the same kinetic energy upon entering a region of

constant magnetic field. What is the ratio of the radii of their circular paths? The α

particle is the nucleus of He atom and has a charge of e⋅+ 2 and mass of

kgkgm He-27-27 1065.6106605.1002602.4u002602.4 ×≈××== [1/2]

5. In a circuit a resistance of resistor Ω.500 is connected in series to a capacitor of

capacitance F 0.25 and an inductance mH 250 and a sinusoidal alternating emf

device operating at Hz50 and amplitude V 0.25 .

a) What is the current amplitude in the circuit? [2/2]

b) What is the potential difference as a function of time across the inductance? [1/1]

c) What is the phase constant φ of the current in the circuit relative to the driving

emf? [1/1]

d)

What is the current in the circuit as a function of time? [1/1]

6. In the figure below the rod moves at a speed of sm /5.2 , is cm0.18 long, and has a

resistance Ω5.0 . The magnetic field is

T 80.0 and the resistance of the U-shaped

conductor is Ω5.22 at a given instant.

Calculate:

a. the induced emf, [2/1]

b. the current flowing in the circuit,

and [2/3]c. the external force necessary to ensure that the rod is moving at constant velocity

at the instance. [2/3]

7. Two first-order spectrum lines are measured by an 8500-line/cm spectroscope at angles,

on each side of centre, of 8326 ′°+ , 8041 ′°+ and 8426 ′°− , 9141 ′°− . What are the

wavelengths? (1/4)





In assessing your work with problems 8 and 9 your teacher will pay extra attentio to:In assessing your work with problems 8 and 9 your teacher will pay extra attentio to:

∗ How well you plan and carry out the task.∗ How well you plan and carry out the task.

∗ Which priciples of physics you use and how you justify using them∗ Which priciples of physics you use and how you justify using them

∗ How general your solutions are∗ How general your solutions are

∗ How well you justify your conclusions∗ How well you justify your conclusions∗ How well you cary out your calculations∗ How well you cary out your calculations

∗ How well you present your work ∗ How well you present your work

∗ How well you use physical and matematical language.∗ How well you use physical and matematical language.

∗ How clear your solutions are.∗ How clear your solutions are.

8. A mass spectrometer is being used to monitor air pollutants. It is difficult, however, to

separate molecules with nearly equal mass such as CO ( u0106.28 ) and 2 N ( u0134.28 ). How large a radius of curvature must a spectrometer have if these two

molecules are to be separated on film by mm00.1 . (2/4/¤)

9. Two stiff parallel wires a distance l apart in a horizontal plane act as rails to support a

light metal rod of mass m that is parallel to the surface of the ground and perpendicular

to the parallel rails as illustrated

below.

A uniform magnetic field B

directed vertically downward (into

the page in the figure) actsthroughout. The system is connected

to a electric power source that

provides the system with a constant

current I .

NORTH

WEST EAST

SOUGHT

a) In which direction does the rod move? Why? Explain! [1/1]

i) East.

ii) West

iii) North.

iv) Sought.

v) Up.vi) Down.

Calculate the speed of the rod as a function of time [2/4/¤]

b) if the rails are considered frictionless.

c) if the coefficient of the friction between the rod and the trails isk μ .


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Test+FyBCh20 21NVC06+Magnetic+Induction+&+AC+Circuits