Questions from College Physics

Q: Refer to Example 28.6. Estimate the percentage change in

Refer to Example 28.6. Estimate the percentage change in the tunneling current if the distance between the sample surface and the STM tip increases 2.0%.

Q: A microwave oven can heat 350 g of water from 25.

A microwave oven can heat 350 g of water from 25.0°C to 100.0°C in 2.00 min. (a) At what rate is energy absorbed by the water? (b) These microwaves pass through a waveguide of cross-sectional area 8...

Q: When on the ground, Ian's weight is measured to be 640

When on the ground, Ian's weight is measured to be 640 N. When Ian is on an elevator, his apparent weight is 700 N. What is the net force on the system (Ian and the elevator) if their combined mass is...

Q: A certain radioactive nuclide has a half-life of 200.

A certain radioactive nuclide has a half-life of 200.0 s. A sample containing just this one radioactive nuclide has an initial activity of 80 000.0 s−1. (a) What is the activity 600.0 s later? (b) H...

Q: Verify that the equation I = 〈u〉c is dimensionally

Verify that the equation I = 〈u〉c is dimensionally consistent (i.e., check the units).

Q: In this problem, you will verify the statement (in Section

In this problem, you will verify the statement (in Section 29.4) that the 14C activity in a living sample is 0.25 Bq per gram of carbon. (a) What is the decay constant λ for 14C? (b) How many 14C ato...

Q: Using Faraday’s law, show that if a magnetic dipole antenna’s axis

Using Faraday’s law, show that if a magnetic dipole antenna’s axis makes an angle θ with the magnetic field of an EM wave, the induced emf in the antenna is reduced from its maximum possible value by...

Q: To perform a bone scan, 3.8 × 106 Bq

To perform a bone scan, 3.8 × 106 Bq of 85Sr is injected into a patient. The half-life of 85Sr is 30.1 yr, and its mass is 84.9 u. What mass of 85Sr is injected into the patient?

Q: You are standing 1.2 m from a heat lamp that

You are standing 1.2 m from a heat lamp that draws an rms current of 12.5 A when connected to 120 V rms. (a) Assuming that the energy of the heat lamp is radiated uniformly in a hemispherical pattern...

Q: A radioactive sample has equal numbers of 15O and 19O nuclei.

A radioactive sample has equal numbers of 15O and 19O nuclei. Use the half-lives found in Appendix B.8 to determine how long it will take before there are twice as many 15O nuclei as 19O. What percent...