This figure shows idealized thermal radiation spectra from several stars and a human. Based on this graph, at about what wavelength does a 15,000 K star emit its most intense light?
A) about 100 nanometers
B) about 1,000 nanometers
C) about 20 nanometers
D) about 100,000 nanometers
A) about 100 nanometers
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An inductor has 200 turns/cm and a cross-sectional area of 1.8 cm2. If its inductance is 32 mH, what is its length?
A. 21 cm B. 15 cm C. 35 cm D. 64 cm E. 72 cm
Single-Slit Diffraction: Radio waves are diffracted by large objects such as buildings, whereas light is not noticeably diffracted. Why is this?
A. Radio waves are unpolarized, whereas light is normally polarized. B. The wavelength of light is much smaller than the wavelength of radio waves. C. The wavelength of light is much greater than the wavelength of radio waves. D. Radio waves are coherent and light is usually not coherent. E. Radio waves are polarized, whereas light is usually unpolarized.
An electron is released from rest at the negative plate of a parallel plate capacitor. If the distance between the plates is 5 mm and the potential difference across the plates is 5 V, with what velocity does the electron hit the positive plate? (me = 9.1 × 10?31 kg, qe = 1.6 × 10?19 C.)
What will be an ideal response?
A 50-turn circular coil (radius = 15 cm) with a total resistance of 4.0 ? is placed in a uniform magnetic field directed perpendicularly to the plane of the coil. The magnitude of this field varies with time according to B = A sin (?t), where A = 80 ?T and ? = 50? rad/s. What is the magnitude of the current induced in the coil at t = 20 ms?
a. 11 mA b. 18 mA c. 14 mA d. 22 mA e. zero