A method for changing colors in a light emitting diode, LED, bulb, the LED bulb being configured to be fitted in a fluorescent light fixture as a replacement for a fluorescent light bulb, the fluorescent light fixture comprising a ballast arranged to output a current to a bulb fitted therein, the current being variable in accordance with a dimming operation carried out by the fluorescent light fixture, wherein the LED bulb comprises an electrical circuit with a first branch coupled between a node and ground and a second branch coupled between the node and ground, wherein the first branch comprises a series connection of a first string of LED lights of a first color and a transistor and wherein the second branch comprises a second string of LED lights of a second color, the second string of LED lights not being connected in series with a transistor and wherein the first color is different from the second color, the method comprising: detecting a level of current being output to the LED bulb by the ballast; and controlling a voltage drop across the transistor by applying a voltage to a gate of the transistor in accordance with the level of detected current, thereby opening or closing the gate of the transistor such that when the gate of the transistor is open, the LED lights of the first string are allowed to illuminate, and when the gate of the transistor is closed, the LED lights of the first string are prevented from illuminating; wherein: when the detected level of current is in a low current region, the voltage applied to the gate of the transistor is such that the gate of the transistor is open and the first string and the second string are configured such that a voltage drop on the first string is less than a voltage drop on the second string thereby resulting in current mainly flowing through the first string; when the detected level of current is in a medium current region, the voltage applied to the gate of the transistor is such that the gate of the transistor is open and such detected level of current causes the voltage drop on the first string to increase such that current flows through both the first string and the second string; and when the detected level of current is in a high current region, the voltage drop on the first string is greater than the voltage drop on the second string and the voltage applied to the gate of the transistor is such as to cause the gate to be either open or closed; whereby, if the gate is open, current mainly flows through the second string and, if the gate is closed, all current flows through the second string; the LED bulb thereby transitioning from one color to another as a result of the dimming operation carried out by the fluorescent light fixture. detecting a level of current being output to the LED bulb by the ballast; and controlling a voltage drop across the transistor by applying a voltage to a gate of the transistor in accordance with the level of detected current, thereby opening or closing the gate of the transistor such that when the gate of the transistor is open, the LED lights of the first string are allowed to illuminate, and when the gate of the transistor is closed, the LED lights of the first string are prevented from illuminating; wherein: when the detected level of current is in a low current region, the voltage applied to the gate of the transistor is such that the gate of the transistor is open and the first string and the second string are configured such that a voltage drop on the first string is less than a voltage drop on the second string thereby resulting in current mainly flowing through the first string; when the detected level of current is in a medium current region, the voltage applied to the gate of the transistor is such that the gate of the transistor is open and such detected level of current causes the voltage drop on the first string to increase such that current flows through both the first string and the second string; and when the detected level of current is in a high current region, the voltage drop on the first string is greater than the voltage drop on the second string and the voltage applied to the gate of the transistor is such as to cause the gate to be either open or closed; whereby, if the gate is open, current mainly flows through the second string and, if the gate is closed, all current flows through the second string; when the detected level of current is in a low current region, the voltage applied to the gate of the transistor is such that the gate of the transistor is open and the first string and the second string are configured such that a voltage drop on the first string is less than a voltage drop on the second string thereby resulting in current mainly flowing through the first string; when the detected level of current is in a medium current region, the voltage applied to the gate of the transistor is such that the gate of the transistor is open and such detected level of current causes the voltage drop on the first string to increase such that current flows through both the first string and the second string; and when the detected level of current is in a high current region, the voltage drop on the first string is greater than the voltage drop on the second string and the voltage applied to the gate of the transistor is such as to cause the gate to be either open or closed; whereby, if the gate is open, current mainly flows through the second string and, if the gate is closed, all current flows through the second string; the LED bulb thereby transitioning from one color to another as a result of the dimming operation carried out by the fluorescent light fixture.