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Unformatted text preview: 1.0 years. The resistance of the circuit in the detector is
B. 5.9 × 104 Ω C. 3.9 × 103 Ω D. 36. 1.4 × 106 Ω 7.0 × 10–7 Ω If the air is ionized by alpha particles produced by the americium-243, what
immediate byproduct would one expect to find?
D. 37. Curium-243
Neptunium-239 Americium-243 has a half-life of approximately 7 000 years. If a detector
containing 20 mg of this isotope were discarded and then rediscovered 70 years
later, approximately how much americium-243 would remain?
D. 20 mg
2.0 × 10–7 mg
No measurable amount would remain. The written-response questions follow on the next page.
21 Use the following information to answer the next question.
A positively charged sphere is suspended by an insulating thread between two
neutral parallel plates, I and II. The plates are connected by wire to a copper
Rod + I II N
Right S A student moves the copper rod to the right in an external magnetic field. The
motion of the rod through the magnetic field causes electrons to move in the
rod and induces a potential difference across the plates. The charged sphere
moves toward one of the plates but does not come in contact with it.
Written Response — 15%
1. Explain the motion of the charged sphere. In your answer,
• describe and explain the movement of the electrons in terms of the direction of the
motion of the copper rod through the magnetic field
• describe and explain the motion of the charged sphere in terms of the charges on it
and on plates I and II
• describe a change to the apparatus or procedure that would cause the charged
sphere to have a larger deflection toward the metal plate
NOTE: Marks will be awarded for the physics principles used in your response and
for the effective communication of your response. 22 Written-response question 2 begins on the next page. 23 Use the following information to answer the next question.
The supernova known as SN1987A reached it maximum brightness, or
luminosity (energy release per second), in mid-May 1987. After that, its
Decline in Luminosity...
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This note was uploaded on 01/14/2014 for the course PHYSICS Physics 30 taught by Professor Quinlan during the Fall '09 term at Centennial High School.
- Fall '09