# Question

(a) When police radar waves bounce off an oncoming car and are received by the transmitting radar “gun,” they have a different frequency than the emitted waves. Explain.

(b) Is the frequency in part (b) higher or lower than the original frequency? What about wavelength? What about wave speed?

(b) Is the frequency in part (b) higher or lower than the original frequency? What about wavelength? What about wave speed?

## Answer to relevant Questions

Two identical strong magnets are dropped simultaneously by two students into two vertical tubes of the same dimensions (Fig. 20.30). One tube is made of copper, and the other is made of plastic. From which tube will the ...In 0.20 s, a coil of wire with 50 loops experiences an average induced emf of 9.0 V due to a changing magnetic field perpendicular to the plane of the coil. The radius of the coil is 10 cm, and the initial strength of the ...A student makes a simple ac generator by using a single square wire loop 10 cm on a side. The loop is then rotated at a frequency of 60 Hz in a magnetic field of 0.015 T. (a) What is the maximum emf output? (b) If she ...The starter motor in an automobile has a resistance of 0.40 Ω in its armature windings. The motor operates on 12 V and has a back emf of 10 V when running at normal operating speed. How much current does the motor draw ...The efficiency e of a transformer is defined as the ratio of the power output to the power input, or e = Ps/PP. (a) Show that for an ideal transformer, this expression gives an efficiency of 100%(e = 1.00). (b) Suppose a ...Post your question

0