In an experiment, which variable do you change? a) dependent b) stable c) graphing d) independent

Modern physics a photon emitted from an excited hydrogen atom has an energy of 3.02 electron volts. which electron energy-level transition would produce this photon? a. n=1 to n=6 b. n=2 to n=6 c. n=6 to n=1 d. n=6 to n=2 i chose b but the correct answer is d can someone tell me why? and what's the difference?

The electric potential v is constant everywhere within a certain region of space. which statement below is true? the choices are: the electric field is also constant (but not zero) within the region. a charged particle placed within the region will experience an electric force. the electric field is zero everywhere within the region. the electric field varies from place to place within the region.

An alarm clock has a current of 4.5 amps and a resistance of 3.2 ohms. what is the voltage in the circuit? a.1.4 volts b.0.71 volts c.14 volts d.46 volts