Answer: the density changed, the salt dissolved in the water, the salt and the water can still be separated into their individual molecules.
Explanation: physical changes are changes in size, shape, or state. Another way to think about a physical change is any change not involving a change in the substance’s chemical identity. You cannot write a chemical equation for salt water because the chemical identity is still salt AND water
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Answer:
C. N/m (newtons/meter)
Explanation:
Since the equation for potential energy for a spring is PE = 1/2kx², after you know <em>k </em>and <em>x</em>, you will get an answer in Joules.
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Explanation:
Given that,
Wavelength of light, 
Angle, 
We need to find the slit spacing for diffraction. For a diffraction, the first order principal maximum is given by :
n is 1 here
d is slit spacing
So, the slit spacing is 
.
Answer:
<em>To reverse the direction of an electric current, we simply reverse the voltage either automatically with the help of some switching circuitry or manually by changing the voltage source terminals connection. </em>
Explanation:
For electric current to flow, there must be a potential difference, usually referred to as the voltage. The electric current flow is analogous to the flow of water under the action of a pump, through a series of pipe connections. The voltage is similar to the driving action of the pump, and current flows the same way water flows. The resistance due to drag on the pipe wall is equivalent to electric resistance. For current to flow in the reverse direction, the voltage or rather, the potential difference is changed, causing the current to flow in the opposite direction. This can be done by switching the terminals of the voltage source, or by automatic means. The automatic switching can be done with a transistor based circuitry.
