物理问题。急需高人指点。1.A guitar string has length of 92cm and the spe

物理问题。急需高人指点。
1.A guitar string has length of 92cm and the speed of wave propagation on the string is 246m/s, what is the frequency of the fundamental tone? Give answer in Hz.
2.What is the wavelength of maximum power of the radiation from a black body at a temperature of 697oC? Give answer in nm.
3.A light bulb is attached to a dimmer. Initially, the dimmer is on the brightest setting and the current flowing through the bulb is 1.1A. The filament of the bulb at this point is 1,993oC. When the knob of the dimmer is turned so that only 0.7A passes through the bulb, what is the final temperature of the filament? Assume that the resistance of the filament does not change as the light is dimmed. Give the temperature in degrees Celsius.
4. A (cylendarical) wire of length 19m and diameter 0.7mm is made from a substance with resistivity 5x10-8 Ohm-m. What is the resistance of the wire? Give answer in Ohms.